Thanks for all the replies! Didn't see them until now, no email notifications!
Had I noticed some of these replies I wouldn't have bought a big 12v transfer pump.
The idea is to have 2 hoses and the pump in the spare wheel well, underneath the boot carpet, lift up, insert one end into the tank, other into cubie, rinse repeat.
I also get to leave the pumping equipement in the car, as I don't have a driveway, so could get annoying lugging stuff about.