Going through this same thing myself. Wife, dog, and I were always fine in a dome tent...we sometimes tow a boat, so trailers are out. Now with a toddler in tow, we'd like a little more room and climate control.
I picked up an insulated eskimo outbreak 650 and plan to add a stove jack, screens for windows, and a trucker tarp floor. Seems promising, but might be tight for all of you.
I dont mind setting up a nice cabin style family tent. I bought a 10 person Turbo tent 5 or 6 years ago, and that thing is like a house. It takes me about 5 or 10 minutes to set it up by myself. Add a bathroom tent, battery or generator for power for lights and stuff, cots, MR. Heater Buddy, a good little camp kitchen, chairs and tables, you can have a very comfortable family camp setup or hunting base camp, for a fraction of the cost of a trailer or RV
I cant get my wife out there yet but go with my brother in law and our kids, we have one of the bigger family style tents and throw in regular queen air mattresses. We obviously don't have bathroom (other than the little potty training thing for the kids,) but bring a table for to set up food, run some standing lights he has from his photography stuff and we are set.
If your thinking about getting a horse trailer with living quarters then it’ll most like be a gooseneck which would mean you wouldn’t be able to have a truck bed camper. It might be worth it just to go for a nice walk tent and heater like the others are saying and put the money you’d spend on a truck bed camper towards your horse trailer with living quarters. If you could get a truck bed camper for cheap then maybe, just got to think about how much you want to spend for how long you’ll have it