The VSR (Voltage Sensitive Relay) has arrived, and I've wired it in. This isolates the camping-battery from the van-starter-battery UNLESS the VSR detects > 13.3V which implies the alternator is running and connects both batteries to share charge. Otherwise at 12.8V it disconnects and ensures you don't flatten your starter-battery by running camping devices for days on end. During winter I decided solar wasn't an ideal means of charging the camping battery exclusively.
The charge cable is some old 15amp 3-core-flex 240V junk I found in Wes's pile at work. We threw out absurd volumes of really crusty heavy guage 3-phase wiring when we moved into the factory and Wes re-wired to suit his business. This was some usable light guage remains and was being stripped down for short wirring in gizmo control boxes and would have taken 20yrs to have been used. It was gizmology material only.
All that remains is to finish sewing up the curtains. I'm waiting on magnets on order to finish them. The magnets will be sewn into the ends to give proper block-out as the van is all kinds of crazy-shape. The spring-wire supports have been hung already. You can imagine the standard campervan white vinyl sheathed spring curtain rails...