Bummer on the mounts, but sounds like you got it licked.

I haven't installed my PSS yet, but don't think it really matters much where you tap into the system for a water source as long as it's under pressure. I think the main mechanism of cooling by the water supply to the PSS is by purging any air pockets around the seal - not by the cooler water temp itself.

It's only a 5/16" hose, so not going to rob much water from anywhere. I plan on using the extra 1/2" FNPT plug near the outlet on my engine water pump.