This won’t suit everyone but I was tossing up between fitting cable joiners through the van wall or just making a hole. I decided upon the latter as it may have other access purposes.

I bought some plumbing bits from Bunnings to use as the hole device.

From the outside it looks like this, when plugged… Unplugged, and perhaps I should have cleaned it up for the pic… I made this plug (resting on my finger tip) from solid ally and fitted an ‘O’ ring for weather proofing. A large cork would also suffice… On the inside it looks like this, just above the fridge, and is also capped… The cap (removed here) is a standard plastic plumbing fitting… The fittings are siliconed in place.

In use coax or other cables are poked through the hole and a bit of foam poked in the outside to keep rain/bugs out. This aspect is not very sophisticated but I expect will work. I thought of making a tiny verandah but couldn’t be bothered.

http://www.candm.com.au/forum/viewtopic.php?f=6&t=4371

I got one from CAMEC, i don’t think they have them anymore.
I can put the TV cable and connector through, plug it up, when not in use.

Hans