Sometime earlier some mentions something about two bolts on the tank removal but don't remember who.
That may have been me. It ain't that
hard, and doesn't require "Terminator" - style tools.
You have to chip away at the fiberglass shroud enough to get to four bolts. There are two on the south side of the tank, and two on the north. (I decided a long time ago to start using N-S-E-W to identify "directions" on the coach.)
The south ones are pretty obvious, the north ones are almost hidden - they are at the very front and secure the front strap. You might have to get at the northwest one thru the inside floor hatch.
After disconnecting all hookups, you can pop the rivets where the top of the chute meets the seat, and the whole thing just drops down for removal thru the side ER door.
Be sho to spray it as clean as possible from the inside and drain before you start!!!
No, it ain't fun but it ain't that
Old clothes, an afternoon, and it's done.