I've got the T230 lwb with 500ltr upright tank fitted across the bulkhead. I've got a gas heaters on the left side of the van towards rear left door. Don't use it much, only for really stubborn f/s/g cleans. Fits in neat and tidy there. Flexible foil pipe on top,so I poke it out the top of the door when in use.
I've got an immersion heater set-up for every day usage though.