Not sure if the OP is still checking in...
Okay, I looked at a couple options in respect to the lines interior to the conditioned space, of concern were the lines feeding the outside shower and the lines feeding the sink at the outdoor kitchen. I considered heat taping and wrapping all these lines, however the run under the shower made that a no-go. So I decided to give myself the option to "kill" those exterior lines when the temps dictate, I looked at valves but decided the cost was not justified. So I elected to make plugs; Each of these sink connections are a threaded flex hose, so I gathered some materials - about $28 to make 4 (disclaimer I already own the crimper ($40)). I will install these / disconnect the exterior sinks when that time comes.
I also decided that "sharing" more of the living space heat would be a good thing, so I picked up some wooden registers that matched the colors well, these are installed in the panels under the stove, the bath storage cabinet (below the drawer), and below the converter. I will open the registers when freezing temps approach, closed the rest of the year. I will do similar to the under-shower access panel when I find a matching register that fits. Speaking of under the shower- HL had to cut into the floor to facilitate the P-trap, this left an open edge of the wood laminate exposed as well as a large section of the foam insulation missing. I sealed the laminate edges with roof rubber sealant and filled the hole back with spray foam. (Side note - the reefer deck / floor is only coated an inch or two back from the exterior hatch, good place to butter while you have the roof sealer at hand.)
The space under the outside sink is now stuffed with fiberglass as well, it is open all the way under the reefer and stove! So something has to be done there as well.
For the life of me I cannot get photos to work (very frustrating, keeps claiming my photo bucket links are invalid?), and this reply box only seems to work if I type approx. 3 words per minute, like the Zootopia DMV Sloth! This is the only forum I have ever had these issues with. Hopefully the thumbs work.......