So, you are a family of 5. You have a tight fitting pick-up truck and a 5er for a trailer. Kids are uncomfortable in the back seat of the truck. You want to take a second vehicle as a chase car. You plan on doing a trip longer than 2 weeks, cross country.
So, who is driving the second vehicle? Are they willing to drive those kind of miles. My wife and I both drive. We switch off so the other can rest (and we usually never do more than 250 miles a day and try to always be honkered down for the night by 5:00 pm, which allows down time, and the possibility of site seeing or doing an activity where ever we are overnighting.
Is the other driver in a state of mind and attitude to be pushing miles like this? My wife and I want to be in the truck together. There's just too much to miss if we are separate. And if you take a second vehicle, which kids are riding with who? Here again, a situation that happens in one vehicle is completely missed and never understood from the ones in the other vehicle. Memories are lost this way. And then, there is the communication factor. With 3 kids and 2 adults, eventually someone is going to need a bathroom. How do you communicate between 2 vehicles if you are in an area with no cell phone reception?
In my opinion, if traveling as a family, you need to "travel" as a family, all under one roof. Use your tow vehicle as your run-around vehicle by disconnecting the trailer at an RV park, a KOA, or a state park. Maybe I'm a bit different in my thinking here, but as a family ... you should all be together under one roof.
It sounds like you have no qualms about purchasing a new vehicle. If that's the case, then bigger is better. After all, those kids will be getting bigger too. And until they start driving themselves and getting part time jobs, they'll be traveling with you. 3 kids in their early teen years can take up a lot of space in the back seat of a cramped pick-up truck. And teen-agers won't want to share a jump seat at all.
If you have the resources, now is the time to get the bigger truck. Look for a full crew cab (full 4 door truck) with full bench seats, front and back. My truck is a 3500 dully Duramax, long bed (8 feet long with a contractor-construction shelve) on the bed. You can still get bench seats for the front, although ours is a split front bench seat, so both halves can be adjusted independently as singles or together as a bench. This provides seating for a 3 person in front... complete with seat belt.
The back seat is also split, but does not move. Each half can be raised, leaving the entire back seat area open. It's great for when transporting people, to have all that space for taller items or lots of cargo inside the cab.
My suggestion, because the kids WILL grow, they are not getting smaller, and your needs are for this moment as well as for your future 10 years, get the truck with a full crew cab now, travel as a family under one roof, and make memories together.
