I live in western Louisiana, roughly around the half way point on your proposed journey so know the region, the weather, etc. I also own a 28 ft class A, so have a good idea about what sites are likely accessible for you. In the second half of February, one can see a wide mix of weather ranging from cool but pleasant days with highs of around 70F and lows of around 50F to highs of 70F (10-21C), or there may be rare hard freezes where with days ranging from 25-40F (-4-+4C). If you happen to arrive during one of these colder weather events I would suggest taking a more coastal route was the relatively warm water of the gulf of Mexico will mitigate the effects of the cold weather, though perhaps also generating dense fog.
Therefore I am going to suggest 2 routes, 1 for good weather, and one for colder bad weather.
First the warm weather route, you may or may not want to see the beaches around Pensacola, the beaches between Pensacola and Gulf Shores Alabama are the western most "semi nice" beaches until one gets down to the southern tip of Texas, they are therefore popular with tourist that don't want to make the much longer drive to the Atlantic coast of Florida, they have sand and generally greenish blue water, which is much better than the many mud flats and brown water along the Louisiana and upper Texas Coast. In February the water will also be far too cold to swim in without a wetsuit. Assuming you will have a mid day pickup and need a place to stop within a couple of hours of driving time on day one I would suggest stopping somewhere around Mobile, AL there are numerous state parks, as well as commercial rv campgrounds in the area. If you are interesting in more modern historical interests, I would suggest the Battleship Alabama park http://www.ussalabama.com/ either on day one or the beginning of day 2.
For day 2 consider taking Hwy 98 across Mississippi to Natchez (250 mile drive in an RV expect about 6 hours drive time), 98 is a good highway, mostly 4 lane, yet rural enough to see some scenery. Natchez is a historic city on the bluffs overlooking the Mississippi river, too bad you a bit early for the Pilgrimage http://www.natchezpilgrimage.com/ there is an large commercial RV park on the banks of the river, just across into Louisiana http://www.riverviewrvpark.com/ where you can watch the barge traffic travel up and down the river (I have never stayed there though have visited with the owners of the park at a local RV show, it also gets good reviews online). From Natchez take the Natchez trace parkway north about 90-100 miles to where it meets I-20 near Jackson MS. https://www.nps.gov/natr/index.htm The entirety of the Natchez trace parkway is nice, though the spacing between historic stops is denser at the southern end, speed limit is 50 mph on the Trace. Unfortunately it goes the wrong direction for your destination, so is only practical for about a half day's drive making many stops every few miles. There is one of the largest Indian Mounds (Emerald Mounds) in the country located about 10 miles north of Natchez just a couple of miles down a small country road off the Trace, I consider it a must stop location. An amazing earthwork considering it was all done by hand with a flat top bigger than a football field. Take I-20 west towards Vicksburg, at Vicksburg go to the civil war battlefield park there is a slow speed drive through the park with many stops with smart phone audio information available (back in the old days they had cassette tapes), the park is RV accessible (mostly) rushing through it takes 2+ hours, though with thousands of stone memorials to troops that fought here one could spend weeks in the park and not read every stone marker. https://www.nps.gov/vick/index.htm. By this point we are getting well of the route to San Antonio, so it is time to head back south, take Hwy 61 back to Natchez and on south into Louisiana. Hwy 61 generally parallels the Mississippi river though never close enough to see the actual river. For plantations I would suggest the St Francisville, and New Roads area, then taking the river road south until you get to I-10 in Gross Tette (this will be the gateway to Cajun Country, and will let you miss the traffic of Baton Rouge).
By now we will be on about night 4, for cajun culture option there are a lot of small mostly cajun towns around Lafayette (though I would suggest skipping Lafayette itself) including Henderson, BreauxBridge, New Iberia, Abbeville, Kaplan, etc. I can't point to any single good cultural point of interest, it is more of a regional thing. One place you might want to stop and stretch your legs a bit is Rip Van Winkle Gardens https://www.ripvanwinklegardens.com/ it is a tropical garden growing on the edge of Vermilion bay. We are probably on day 5 or so now, so time to make up some ground, and head west. You are within a full 8 hour days drive of San Antonio, where you must see the Alamo and probably the river walk. If you have time you may want to consider a side trip to Fredericksburg about 90 miles Northwest of San Antonio. http://www.visitfredericksburgtx.com/attractions-activities/ http://www.pacificwarmuseum.org/ http://www.luckenbachtexas.com/ One could spend a week within 10 miles of Frederickburg and still not see everything there, the war in the pacific museum could easily take 3 days by itself.
Now for bad/cold weather route with more indoor stuff to see and do.
We still have the Battleship Alabama in Mobile, then go west to New Orleans, ( try to stay out of New Orleans as much as possible, excluding the french quarter tourist district, the city has one of the highest violent crime rates in the US). You can find many cultural and tourist things to see and do in New Orleans you don't need me to list them for you. Going west again visit New Iberia, Abbeville, Kaplan, etc for cajun country. You will be in the middle of boiled crawfish season during your visit and there will be drive up boiled crawfish stands in every community (several in each actually ), so consider dining on a few along the way. From here you probably want to go back up to I-10 around Crowley, though is you are up to it consider the coastal route along Hwy 82, the road tends to be narrow and rough though, making stops in the nature refuges, and along the creole nature trail. There is very little left along the western Louisiana coast since Hurricane Rita wiped it out 3 weeks after Katrina hit New Orleans in 2005 (still depopulated by over 50 percent from pre storm levels which were not much to begin with) Take Hwy 82 in to Texas then 73 west towards Houston, consider some of the tourist options in Galveston or Houston, though be aware of Houston Traffic. If you want to avoid Houston on your way to San Antonio consider taking TX 105 west from Beaumont, it is a good highway though mostly 2 lanes, I drove it in my coach in the last year, then take one of the highways down to I-10 once west of Katy, or take 290 to Austin and make the side trip to Fredericksburg.
I hope this has been of some help
Ike
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