Note that I am in AZ.
I run a Holley 770 on my magnum.
3/8 lines up and back for a return system with both lines routed up the corner of the firewall and inner fender insulated then across to attach to a flipped backwards
dual fuel feed hard line.
My return T is right before the hard line that screws on the carb bowls.
I put a gauge in the main feed and a restriction orifice in the return to give 7 pounds at the carb. (no regulator)
I run an electric pump, but see that you use the mechanical, so obviously you pretty much have to have the pump to carb line up front in all that heat.
If you put a return type filter on it you will want to put it as close to the carb as possible to get as much of that hot fuel out of the main feed as possible before it goes into the carb.
The return will very likely solve hot fuel and possible vapor lock issues, but it sounds like you also have an electrical problem somewhere caused by temperature.
