Mike:
Thats a ruff Idea. Heres why? Pumping Gas from your house boat without containment sacks or ways to catch the overspill, is a huge fine by the coast guard or any agency that reports you. Even transferring gas from a 5 gal to the boats gas tank, on the water, is a fine.
Gas Dock have to go through a bunch of hoops, before they can pump 1 gallon. You might want to talk with them. See what they did to transfer gas. We looked into this for our wakeboard school and found that it was a pain in the ass to pull each boat out of the water, but it was cheaper than getting caught.
Our insurance company would cancel us in the event that happened. Reasons, would be negliences. So, Thats what we learned this winter. Not saying it cant be done.
Good Luck Mike
Ric Morgan
www.learn2wakeboard.com