Depends on the cabin and your accomodations. I will assume you get your won small room..double bed probably. Bring a pack and play to sqeeze in against a wall for him to sleep in and "play" or be in while you shower (a safe zone for the 15 minutes you need to be hands free, etc..while you shower and hubby dresses, etc). Bring his own blankets, a sheet for the pack and play, etc.
We have always gone to my in-laws cabin...a house really but not quite a house I would agree to live in full time..but works for a cabin on the lake. When my daughter was little she was terrified of the tub..and theirs was not the greatest...the other bathroom was just a shower...so we either bathed her in the kitchen sink, or in one of our storage Rubbermaid containers that we brought our junk up there in (we ahve a pick up truck and using these containers, with bungee cords to make sure the lids stay on is the easiest way for us to haul our foods, her blankets, her toys, towels, etc. They were then waterproof and could be out and exposed in the box of our pick up). Often I just emptied one, filled it with pitchers of warm water from the sink and bathed her wherever it was ok to (on the screen porch....outside if it was mid-day and no skeeters...or just put that container inside the sorta icky like tub so no water got all over the floor or carpet elsewhere...worked for us!
I think if you have your own small bedroom, the rest should be easy-peasy and fun!