I'm not going to address the questions about your tow vehicle, but I'll chime in on everything else, from (our) experience!
Like you, when the kids got out of High School, we switched from a Pop-Up to an 18 foot 4 walled travel trailer (See my profile page).
My daughter has teased us ever since, as he says we are not "really" "camping" any more. And actually, she is right. We're not "camping", we are RV-ing. So, when the kids start teasing you about not really "camping" and why did you wait for us to leave home to get a "real" trailer, just respond with a couple come-backs.
1) When you have kids, you don't have disposable money. Now that YOU are out of the house, we can enjoy some luxuries for ourselves that we could never do because we had to feed YOU! (that shuts them up pretty fast!_
2) Remind them, you are NOT camping any more. You are now "RV-ing".... The kids become speachless and simply do not know how to respond! It's priceless!
OK. Now that, "that" is out of the way, let's move on.
About "longer" trailers? We went form 18 feet, to 31 feet, to 35 feet. We camp every opportunity we can. We go everywhere. And because we are able to park the camper at home, we use the camper through most of the winter too at home. We use it for extra bed room space, an office, and sometimes, just to enjoy it. We use it a lot! On the road and at home.
About the size and type of camper. Trust me on this one! Your parents had the right idea. YOU as the owner of the camper should NEVER have to sleep anywhere else but on your own bed! If ANYONE wants to go camping with you, they should take the secondary sleeping spaces, even if that is a tent outside! NEVER give up your bed. It's yours. Be FIRM on that, or you'll find yourself sleeping in the tent!
For us, we finally got "over" the idea of having to accommodate the kids and grandkids! If they come, they can "ruff it". It won't hurt them. Our current camper is designed for 2 adults, and pretty much, that's it. When my son comes with us, he sleeps on the couch (we removed some furniture and had a household size couch with recliners built in to replace it all). He sleeps on the couch and his 2 and 1/2 years old son sleeps on the pull out hide-a-bed, blow up mattress sofa that came with the camper. It works VERY well this way! Every one is happy!
When our 3 grand daughters are with with us, they sleep where ever they want. On the couch, on the floor, with us. We don't care. Their Mom and Dad sleep in a tent. They want their own "privacy."
So, when selecting your camper, be a bit selfish here! Get a camper that will accommodate YOU forget about accommodating the rest of the world. It's YOUR camper, not theirs! (Believe me, in time, you'll REALLY understand this!) Get a camper that will fit your needs (just the 2 of you) and anyone else that happens to come along, they'll have to figure out how to fit in! You will NOT always have additional family with you. When it's just the 2 of you, you'll look at all the space you can't use (extra bunks, extra bathrooms, etc), and wonder why you are paying for something you can't use.
Also, taking the kids and grand kids runs in spurts! 90% of the time, we camp alone, no kids or grand kids. I simply cannot see accommodating 50% of the camper to something that gets used only 10% of the time!
When we got our first camper, we took my mother camping with us quite a bit. The camper we selected, we considered accommodating her. That only lasted one season and then she didn't want to go any more! We learned REAL fast!
The second camper, we considered accommodating my wife's Mom and Dad. We did. That lasted only 1 trip! and that was it. They bought their own camper, and believe me ... it had no way to accommodate more than 2 people only! So we had a camper for 7 more years, and part of it we never used. Why???????
So, our 3rd camper. We said "Phoey on everyone else!" This is for just us 2. And it's worked perfect.
OK, I've rambled enough.
Everyone one of us has o make our own choices. These are my experiences. Your thought process may be 1000% in the opposite direction. That's OK if it is. That's the beauty of camping. It's something we all do in our own way! No right or wrongs here!