Thought occurred to me, can you just use a tank outlet/ bulkhead fitting, available in 3/8” size, just need to get a fuel comparable washer for the seal.
https://www.discounthydraulichose.com/mm5/graphics/00000001/00397-06-PNG.png


Hank: 46 Chev 1/2ton shortbed
2023 Miata RF Club