I drove the truck and camper over Parley's Summit on I-80 to Park City on Saturday (101 degrees when I left the valley), then repeated the trip the next day with the trailer in tow. There are more brutal climbs in the West, but Parley's is a pretty good indicator of what to expect on a long uphill.
The camper and the trailer did great. They ride well and nothing's coming loose or falling off.

I deployed all the moving parts when I got home to make sure everything is working as it should.
It was the first time I'd tested all of the jacks together, and they're all working fine. Some of the drawer and cabinet catches need to be adjusted, and the inverter configuration isn't quite dialed in, but it's getting close. I've also decided to extend the tongue of the trailer 16" to give me a better turning radius once I swap out the ball coupler for the pintel/lunette.
I really haven't driven the truck since last summer, except for back and forth between the shop and the storage unit a few times. It was running hot over climbs last summer, but I never boiled it over. I just backed off and took my time. I had the same experience on Saturday and Sunday. I couldn't do the two steepest sections of the climb at more than 35mph in order to keep it at the 3/4 (230?) mark or cooler on the gauge. I can't see any coolant leaking, and the cap appears good. I'm taking it in on Thursday to have them check the entire cooling system to see if something's up with the T-stat, clutch fan or maybe just a gunked up radiator. It maintains normal temp on the flats, even at 65-70. If any of you have experience with Topkicks, let me know if you've had similar issues.