how neccesary is a return line for a electric fuel pump?

I think the newer model Mustangs have a pump in the tank along with a regulator, the fuel from the regulator just returns inside the tank. They don't dead head the pump pressure I believe.

Corvettes have a variation on this as well. The return comes off in the rear of the car I I believe at least the regulator is external. So it's a return, but does not go clear to front of car.

There are advantages to both types