I'm looking for suggestions from anybody who may have experience with gas tanks under wood beds in trucks.

I made a tank for the rear of my pickup and I'm just now assembling the bed and unsure of how to interface the tank
inlet with the bed so that it looks good.
I welded a piece of pipe on the tank inlet that sticks up about 1 1/2" or so. I'm not sure if I should try and connect the tank to a door on the bed, or just have a door on the bed that opens so that the tank can be seen. . . and then I guess I'll have some sort of a flap and twist cap on the tank.

The bottom line is, I don't really know how to go about this properly. Does anyone know any places that sell parts for this kind of thing?