We just bought a new travel trailer. Manufacturer spec is 4,000 lbs dry weight. Now we need a tow vehicle. We are considering a 2006-2010 Ford Explorer with V8 engine and class IV WDH. Does that sound adequate, with some left over? I know that GVWR, GAWR and GCWR all come into play but I haven't gotten that all figured out just yet. I also want to be sure we aren't maxing out the system and unnecessarily putting excess strain on the TV.