Trouble installing new tank

Obviously it can be done with the tube in according to others here. I know mine in the Duster was hanging onto the tube, but then when its all wide open in the trunk its a no brainer to get it out of the way. It sounds like your big dillemma is getting to the floor seal. Any reason the tube can't slide through the seal without pulling everything else out? My tube on the duster attaches with a flange from the outside with screws under the cap - then it slides out . You already have the tank out, so how bout cleaning up the bottom of the tube, lube it a little, and slide it up/out? You would only need to pull it to the seal but not out. I wanted to replace my gasket on outside panal anyway so it had to come all the way out the side.