ok..... your going to get made at me butt... ahhhhh
they make three port fuel filters just for this. Well sorta just for this.
They are for gasser cars prone to vapor lock without them. 80's 90's era I think. There are many configurations (where the third port is). Third port was for bleeding fuel vapor back to the tank where it condensed back to liquid.
Find one at your fav. cheapo Auto parts and plumb a line off the third port to an air valve like yours or find a way to do like many older MB diesels do. Just run it to the tank as long as the tank is vented. Any fuel that goes up the line goes back into the tank.. Any air that makes it there gets vented out.
are bike fuel tanks vented?
Fancy way I guess would be if your custom building then weld in a small tube that goes up from bottom of tank thru the inside and out the top. Hole drilled in tube just below tank's top. Weld the tube to the top on the outside. Cut it of flush and weld it closed. Grind it down so its invisible. Only suggesting welding to top for added strenght. Maybe a one way valve in this tube to let fuel and air up.. but none down. Then you could plumb the third port for bleeding air into the bottom of the tank and let it send air and any other fuel up thru it to the top of the tank and out that hole drilled in it, Whala..... a fuel return that bleeds air.
easier option might be (if the tank is vented) is to drill a hole in the fuel cap and plumb the third port into that. Would look sorta like the old dirt bikes that had a hose on the fuel cap. What the heck was that for? Vent Im guessing
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