Curious, fuel tank pickup hole size/options

I currently have this - FiTech Gas Tank Return Line Bung Kit, For Fuel Injection - No Welding | eBay - I don't think it requires any sort of welding/brazing.

My brother also suggested I run it into the filler tube but I also would prefer not drilling holes in that either. The sending units are under 100$ for basically any of this design.

I'm looking to make my own sending unit out of one with the correct size locking ring, I am capable enough to bend tubes and floats to achieve what I need or at least close enough for who I roll with so that isn't a stopper, just the size of the locking hole in the tank. Stuffing as many things in one hole as possible! =D

I'd prefer return in sending unit > filler neck > hole in gas tank. Gettin close to firing up. This summer for sure!