You'll need a 12/240 v fridge (Waeco,Engel type in car to keep that cold beer close at hand I reckon.
If your not setting up for long periods of time you probably wont use the annexe walls, maybe 1 end but not the whole annexe.
Maybe a ground mat thingy.
Maybe a solar thingy too.
Oh yeah dont forget the beer.
Happy trails and welcome.
Cheers Glen