We got the snout flap hinged today. We’re planning a swing arm that will keep the snout closed until we need to empty the tank. I don’t know how well it will work . . . time will tell.
We also got the snout added to the tank. For the inside of the tank we cut a ring flange that was stuffed into the end of the inner tube before the inner tube was run through the hole in the tank. The outer flange is the same material as the inner, but other than trimming the edge that wanted to stick beyond the back side of the tank, we did nothing additional.
The bolts heads are on the outside and are slotted and almost flat. I don’t know how good the seal will be. Again, time will tell. It doesn’t have to float, so I’m not going to worry about it.