>>536102>Anyone know a good way to clean out the water tank?Pull that water tank right out of there and use the space for storage, which is far more valuable.
You don't a 9000 gallon water tank nor do you want to hail that additional weight.
A couple of 5 gal jerry cans is sufficient, as you're probably never going to be that far from a water tap anyway and even if so, refilling a jerry can is easier then hauling the entire camper to the water source.