My best friend brought this portable hot shower system on our winter grand trip and it was THE saving grace of the trip.
Here it is -
Extreme Self-Contained Portable Hot Shower | A complete System with convenient Stove | Zodi.com
That, an extra propane tank, and a cheap pop up shower tent (https://www.amazon.com/OutTopper-Wat.../dp/B06XH6T7WF
) equals hot shower/sauna goodness for all. It was soooo nice, really boosts the morale knowing at camp you can take a hot shower after a cold day in a soggy dry suit.
If you have the space I’d also recommend bringing an extra dry bag packed with some spare warm clothes and a couple spare sleeping bags, just in case. Maybe even a spare dry suit if you can get one. We had a couple people hike out at Phantom and they left their dry suits behind so we could use them as spares just in case.
Also, to tag on to what others have said, bring stuff to maintain/repair dry suits. Gaskets would be nice, also some zipper care stuff, maybe some 303?
Then of course duct tape for the stuff that moves but shouldn’t, and WD-40 for the stuff that doesn’t move but should.