I just read through this whole thread and think you should take a step back and consider a different trailer instead of upgrading your tow vehicle. There are plenty of smaller options that can fit your family just fine. For a first time RV experience you may want to consider buying used and much shorter, with no slide. With an upper bunk, lower double bed, and dinette you can sleep your whole family. We had a Milan 18 footer with that configuration that weighed about 4,500 lbs all-up with gear and full tanks. Doable with your tow vehicle and much easier to get around with than a 28'. It also had a couch in the front and cost $13K new.
There are many ways to RV, but you don't need to jump in with the ultimate setup. Plenty of time to upgrade later once you know what you like and don't like. Go with the tow vehicle you have and get a trailer that fits it.