I would take the lower mileage 2018 base - especially if it's being sold CPO. My use case is pretty similar to yours. The only thing I like about the Lux model is that I think it has power-folding rear seats. I believe there's a way to tap into that power to reliably power a portable fridge. The rear outlet in at least the 2017 Premium, which is what I have, is woefully inadequate.
200k is up there and I think you'd have to expect shorter remaining life with things like gaskets, seals, and anything rubber. The parts themselves are probably cheap, but if you don't or can't do the work yourself it could get expensive.
My brother has a 470 and the airbags blew out on a camping trip. I think it had a little over 200k miles when they popped. He got it used for a good price at the time. He's not the type to do anything more than his own oil changes and early on he's had to replace CV axle because of torn boots, a transfer case seal on the actuator or something like that, probably some more things I'm forgetting, and now the most recent thing is a rear axle seal.