Relocating fuel tank, what to do with old filler neck hole?

[jcwren]

I ordered a Boyd in-frame fuel tank today, because I just really don't like the idea of a 17 gallon fuel-air bomb right behind me, nor the gassy smell around the cab.

The truck has already been painted, and I'd rather not leave a gaping hole for water to get into . I'm sure a patch can be welded in and blended, but I'd rather not do that until everything else is done. Does anyone leave a dummy filler neck and cap either for convenience or appearance?

The in-cab tank was installed in the truck before I bought it, but had never had gas in it until a few weeks ago. I'd rather not carve up a perfectly good new tank for the dummy filler neck. Anyone have an old tank they'd be willing to chop the neck off and donate/sell me?