Well I did it! Figured it I put 6 gallon in on the way to the lake this last weekend I'd be empty when I got home. I put 12 gallon in to be safe. Got a total of 535 miles, got home and pumped out 16 gallon. The tank is larger than 80 gallon or I got better mileage the 320 miles I drove w/o the toad. Pulled the fill tubes off.
Dropped that tank.
Had to grind the heads off the clamp bolts that held the tubing over the gray water tank to get them out of the way. Unbolted the Generator tube and was able to force it back 6 inches to get to the hose clamp behind the gray water tank on it. I do not understand why Airstream put such short tubes for the return, vent, and generator lines leaving then to terminate out of sight behind the gray water tank. Removed and replaced the return steel line with larger line from the front to the just before the gray water tank to accommodate the EFI. Of course I had to buy myself a high dollar flaring tool to flare the steel lines (I've been wanting to get one for years)
Put all new clamps and hoses, jacked that tank back into place. Poured (and splat) 10 of the 16 gallon I took out back in the tank.
Time to start it and leak check my handy work. Got her started and the fuel pressure gauge pegged and the engine rans ruff, smoked like crazy. The neighbor came running thinking the barn was on fire. Well something is not right. I drop the tank and I got the return and vent hoses under the top tank support. Got that right and she runs just like she should. Now all I need is someones credit card and got fill-er-up to the tune of $250!