I’m amazed my post stuck to the wall this time.
Since you live in Seattle, an all aluminum camper is a splendid idea. Be sure to get an all season package in whatever you wind up with. My choice would be the Lance 650 as it has the 4 season package that works to reflect heat and and retain heat in cold weather and works on a shortbed truck. It’s also the least expensive camper with all those weather features you will find.
2020 Ford F-350 XLT FX4 4WD SRW SB SC 7.3L Godzilla Gas TorqShift 10R140 397 amps dual Alt dual batts Frnt Dana 60; Rr Dana M275 E-locker 4.30's 4580/4320/4066# payload 7243# curb wt. 11,300# GVWR 5-er prepped. 2020 Northstar Laredo SC, 12v compressor fridge, cassette, 320w Solar sub zero insulation.