In particular, be sure they show you how to set up the water heater including setting the water heater bypass. It'll probably come to you in the bypass position. Then be sure they show you the details of operating the fridge on each of its three power sources. Those two subjects are hard to explain meaningfully online in case you would post questions about them later.
And never start to pull a trailer without being sure you can stop it. To that end, have them show you how to adjust the electric brake controller. Better yet, have them adjust it for you. If this isn't your first trailer, though, you probably have the brake system well in hand.
After you get home, remember: we've got your back, my friend! Send up the Bat Signal if you need help.
It's never too late to have a happy childhood!
Lee, WU0V, and Courtenay, N0ZDT
2011 Rockwood A128
2000 Silverado 1500 pickup
60W solar system
2000W inverter generator