OP here.
Thanks everyone for your help. I appreciate all your input and concern for the safety of my family! The overwhelming majority appear to believe I would be crazy to pull anything bigger than a tent trailer. That, unfortunately, is what I just sold. It was a "really nice" tent trailer. I was pulling it with a minivan and a 3600lb towing capacity. We took it up through the mountain passes without any problems. We did stack up all the kids on one bunk and it worked for making some good experiences. I guess that I just thought that my options would open up a little more with a 8500lb towing capacity and HD tow package. :( Sounds like most even feel a hybrid, which says it is rated for SUVs, won't do. I'll just have to take all your advice and pray about it.
Here is my short term plan. I am going to try renting a hybrid that is close to what I want to buy. Load it up like normal and take it to a scale to make sure I am balanced (10-15% tongue weight). Then take it on a trip and see how it handles on the job. If it can't do it now, with 5 little kids, it will never do it with older kids. In which case I either take 2 vehicles on the trip, upgrade, or tap out.
It may seem like I have money to spare because I got a Lincoln Navigator, but it is a used 2009...20k$, not the usual 75k$. If it comes down to having to buy a new vehicle right now, trailer camping might just not be for my family. I'll have to wait until I fit the trailer camping stereotype a little better when I am old and retired. I'm really against going into frivolous debt and I'm trying to live within my means.
