Return line fitting

Well I personally run a fuel cell, but It could be no different then what you have. I run 1/2" line for feed and return. My cell has two sump outlets one blocked off and the other feed the pump. I run my return line in the top of the cell which you could also do to your tank. All it requires is a bulkhead AN fitting and a hole drilled for it slide into. The AN fitting is your typical AN fitting with a threaded nut and nylon washers. The right size hole gets drilled the fitting set in with washer on both sides and the nut holds it on from the inside. So your placement in the tank needs to be reachable from the outside to fit a wrench on it. You could put it reasonably close to the factory sending unit and be able to get access.

I personally dont like the location of the factory unit on the wall of the tank. I never like a sealing point that is sumerged all the time. Infact thats waht pressed me to switch to a cell. I faught several attempts to get the factory unit to seal then finally gave up and move to a fuel cell. If it were me I would place the return line onto of the tank.