Having done just the opposite (TC to 5th wheel actually) a few years ago, my inclination is to say that I'd advise against this transition. However, facts and observations are probably more valuable than my opinion; your perceptions and tolerance levels for certain things may differ from mine.
1) My TC weighed about the same as the Lance you are contemplating. It was way more of a burden to load, unload and haul than the 30 foot fifth wheel we swapped for. Obviously a fifth wheel may be an unfair comparison to your TT, but my Dodge 3500 is way more steady and comfortable with my conventional hitch boat in tow, weighing in at 12,500 with no sway bars, compared to two tons of camper in back. Yes, I too was out of weight limits with my SRW 3500 and the TC. It never really scared me, but I was hanging it all out there regarding liability. It would have been indefensible if I had been involved in an injury accident. There are already too many over weight recreational vehicles on the road, including more than half of all TCs by my guess. Don't be one more of those who disregard the limits please.
2) Heed what others have already mentioned; weight limits. You are way over GVWR with just a 3900 base weight slide in camper. Add fuel, supplies and other gear, along with your wife, kid and dog if you have one - it's as serious weight exceedence. Some folks will say "well, as long as you don't exceed tire or axle weights, you're okay (I disagree), but even those limits require close scrutiny for your situation. Forget about adding a horse trailer with actual horses on board. Nothing short of a F-350 DRW is going to do what you propose within weight limits and safely.
3) Cost: chances are your Lance will set you back more money than your TT can return to you. You will be in shock over the relative value; huge space and abundant amenities for pennies on the dollar with your TT, and a lot of compactness for a lot of money in the TC.
4) Camp set-up: with either rig, we wanted local transportation if camping for more than one night in a particular spot. The TC is a PIA to drop and level compared to the Fifth wheel. And reloading is several magnitudes more difficult with the TC. Sometimes we would use leveling blocks under the truck tires to get close to level, then unbuckle the tie downs and fine tune the level with our jacks. Good for one night, but tough luck if you need wheels to go exploring.
With all the above said, we plan to keep the fifth wheel and buy a light weight TC, just for the purpose of back country access. And for the possibility of towing a small boat, or whatever. I love truck campers and they clearly fill a very specific niche in the RV world. But what you are envisioning appears to be a recipe for disappointment. The capabilities you seek are not available with that camper and an F-250. But the point I'll emphasize the most for your family situation is the relative level of comfort. It's like moving from a third floor tiny apartment to a large house in the country. Our first time out in the TC, it happened to snow on Memorial Day Weekend. Sure, that small space gets nice and toasty with the furnace running and a stove burner preparing hot chocolate, but what had been planned as an outdoor day ended up as a huddle around the dinette playing board games. The kids were whining and miserable. Each time we visited a neighbor in their trailer (similar to what we ended up with later), we were in awe regarding their space and comfort level. Will we enjoy a TC once again, especially when it gets us places our fifth wheel would never dream of? Of course. We know exactly what to expect. And that the alternative would be a tent. We also will have the big rig available when camp access is less of an issue. Good luck with your decision. You're off to a good start, asking questions.