Best shower on the circuit is outdoors at Hallett. Loud gens are annoying but then again almost any gen is loud enough to keep me awake. Depending on the track I bring all my fuel especially for Hallett.

Don't see how you could put all that into a 20' trailer and have room for the car either. I prefer staying in the track in the trailer. Hallett has some electric plugs you can find that you pay for but not sure how many are around that aren't a part of a raceport.

I'm not a fan of using a half ton vehicle with an enclosed trailer though I have only used a 3/4 truck/suburban. I know tow capacity's are claimed pretty high on some new half tons but have to wonder how they really handle a trailer under braking, in wind, etc. Plenty of people do it but I question the safety and durability of it. But I understand the compromise of not wanting a 3/4 ton truck to drive everyday and not want to pull a 40' bumper pull triple axle.
I'll throw out considering selling both trailers and the yukon then using the Excursion to pull a 24 or 28 depending how much stuff you want to bring or if you want some living quarters. Take the Yukon for a 100 mile test in the wind/heat towing the trailer loaded with all the junk we bring to see how it does before making a big change. See if you can monitor trans temps in overdrive if you have the 4l60 which I assume you do.

Lots of variable and what you want will change so doing a test run before a huge change is my suggestion. I wouldn't worry about being hobo-ish no matter what you do either.

Does one need to have a co2 monitor if running the truck all night and sleeping in it? I'm told motorcycle guys rent diesel vans and leave them running all weekend.