I am not too (of course some) worried about not having a permanent cabin. My adventure for next summer is to backpack the Colorado Trail (500 miles from outside of Denver to Durango). I have a ton of experience backpacking. When I backpack I only take a tarp, no tent, it actually works better overall. When raining there is no waiting it out (unless no other choice), you wear the proper clothes and march on.
I know it is going to be different traveling by boat but I don't think a permanent cabin is needed, but I don't have the experience yet to back it up. I am thinking that with the bench storage, dry bags and a dodger I should be OK. Even if everything is wet and raining when stopping for the night it shouldn't be much different than when I backpack. You setup the tarp (dodger/boom tent) first to prevent further rain from coming down on you. Then you have an environment underneath with no more rain to get out of your wet clothes and get dry stuff out of your pack (bench storage). You use a dry ground sheet over the ground (sleeping platform) so that you can lay down on something dry. I could also bring a bivy sack to further protect my sleeping bag.