You should return to the tank. I am betting that the microprocessor will function better as originally designed. If you have the fuel line for the return just zip tie it to the return coolant line. Unless you are in Alaska it will work fine if you are in Alaska wrap it with insulation. This HOH (Hose On Hose) works perfectly and especially if it is just the return line.

If you really want to loop it. Two valves work fine. I could not see your diagrams. Sorry.