"Path, I thought about a roof like you did, but did not ask at the park yet. Are your vents all still usable? Can you send some better pics of how it is constructed? Does it just sit on the existing roof?""
(Answer) RV Roof is from a couple camp spots up from me. Although I've have helped out on 3 of them. You have to watch weight due to new weight is on top of existing trailer. 2x4's 16 or 18 inches on center with 3/8 or 1/2 sheeting. Yes, vents on rv still work however you have to have enough venting on your new rv roof cover for rv vents to do any good. Hence light doesn't come thru like your used to. And make sure you leave enough room room for a/c. Don't have any other pics or drawings. It is just a big wooden frame with 2x6's as base frame and 2x4's as roof supports. Spend extra time on 2x6 base making good use of a square. Once you get 1 angle cut done for the roof, you can really knock the thing out. On 1 roof we extended all vents; refrig, tank vents and it really didn't make any difference. On another we put in skylights to match up with tub skylight and kitchen vent, worked OK when sun was directly at right angle. Not worth the trouble to mess with in opinion.
When building-- think keeping dry and not how sturdy you can make it. If your base is square that is 3/4 of battle. Usually went with1 foot overhang and peaked roof not rabbit hutch style. Price out materials at today's prices maybe it won't be that much cheaper the way prices are going. An bear in mind once you put a roof on it you won't be towing it any time soon. I wish our park would allow a pole building type, would be bets of both worlds.