The minimal amount of towing you plan to do should not affect the lifespan of any vehicle designed for towing. The idea of a caravan is something to think about if the wife is OK with the idea of driving 2000 miles by herself with 4 screaming kids in the car with her. If so I'd get a 1/2 ton truck, set up for max towing, as the tow vehicle. That's for a reasonable sized travel trailer no 38 ft long behemoths.
If you want to tow big then a HD 1 ton truck would be the way to go, huge travel trailers or fifth wheels. Forget about 3/4 ton trucks no matter what they make no sense. When I say truck I mean one from the three US manufacturers. A one ton is slightly more costly than a 3/4 ton and will be a more capable tow vehicle. You can expect about 17 mpg on the HD truck and maybe the low 20's for a 1/2 ton when not towing. When towing that can drop way down on a gas engine, possibly all the way to 6 mpg. And if you want a really big fifth wheel, over 35 ft then you will be looking at a dual rear wheel truck.
Frankly we did not start camping with the kids until they could all walk on their own, at least for a fair distance. Probably 5 or so. We recall the hike in he$l out in the Smokies when it was 90 degrees and the young kid staged a sit down strike and had to be carried back. And we ran out of water too. This was out to some knob and there was a fair amount of up and down on the trail and no shade. We had three kids.
However Disney should be safe. I have never seen a bunk house with 4 beds tho. Maybe dual stack them in a bed when they are small.
Arctic Fox 25Y Travel Trailer
2018 RAM 2500 6.7L 4WD shortbed
Straightline dual cam hitch
400W Solar with Victron controller
Superbumper