Stake hole gas cap / filler neck questions

[Gordonr1973]

Hi guys;

I bought these gas cap and filler necks on e-bay, of course no instructions came with them & I'm having trouble trying to figure out how to mount them through my stake hole in the bed.

Would you recommend cutting a hole in a piece of sheet metal, fitting the bung in the hole and then tach welding it in from the bottom to keep the seam clean around the top?

Then I could weld the sheet metal into the stake hole (would probably have to cut the stake hole bigger to fit it).

I'm wondering if there may be a different way that I'm not seeing because the bung has grooves cut into it that makes me think that it somehow just might push into a hole and then get clamped from underneath to allow it to be removed later on down the line for servicing.

Help! :-)