I relocated the thermostat control on my R23 from the cave to the v-berth so that it's easier to see, and responds to the v-berth temp rather than the cave temp.
It's a pain, but doable in an afternoon (~4hrs). The thermostat has quite a long cord, and the actual unit sits under the forward dinette seat, so moving it anywhere forward of the cave on the port side is within reach.
My first thought was mounting it next to the radio, but I decided against that because that would put the thermostat in direct sun and affect the reading. Instead I put it just inside the v-berth entry, on the port side wood panel that's above the sink.
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There's a few challenges...
The cable is zip-tied in a wire bundle that's tucked up inside the top of the cave. I took the slow, tedious approach of unscrewing each zip-tie mount, loosening the zip-tie (you can jam a flat-head screwdriver into the locking mechanism to release it), pulling the thermostat cable out, and then re-tightening and re-attaching the zip-tied cable bundle. It would be much faster to just cut the zip-tie with wire cutters and replace with a new one.
To get past the wall that separates the dinette from the v-berth, you have to drill a hole from within the forward end of the cave. I choose to go just under the hot air duct, as I figure a smaller hole wouldn't matter below an already-bigger hole. But from that location it's not very accessible from the v-berth side - the shelves and wood panel behind the sink are in the way. I didn't want to disassemble everything, so I managed to push the cable through, then snag it with a hook of stiff wire and pull it out behind the wood panel. It would be much faster & easier to just disassemble the whole shelf assembly and remove the wood panel.
I would definitely do it again though, it is worth it to have the thermostat in an easy location for viewing & adjusting, and for using it while sleeping in the v-berth.
I've uploaded additional pics to my gallery, album:
Relocating the Webasto thermostat