Routed the "vapor" outlet from the black vapor separator to a (new) fuel return line that goes to the lower (smaller) spout on the tank, and routed the existing line from the trunk vapor separator up to a hose that tees into the hose leading from the PCV valve to the air cleaner.

Fuel pressure maxes out around 6 psi and bleeds down promptly when the engine is shut off. I think I fixed it.

I also learned not to unplug the return-line spout on the fuel tank when the tank is 3/4 full. I think that was the most gas I ever spilled on myself.