in that case, a vac gauge would be before any pump, and the pressure gauge would be best after all filters- that would indicate a clogging filter by decreased pressure.

have you looked at oil pressure gauges? cheaper. I'd still go with electrical, so no lines in the car.

I took a page out of the big trucks book, and installed a vac gauge after my switching valve. it gauges resistance on both filters.
this is on my cummins-
tank(s) to valve, vac gauge, filters, Lift pump, IP.

I dont see a need for a boost pump, especially if you have a heated tank, lines. those LP's pull alot of pressure.

__________________
1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.