build a drip stove first. when you see how easily they can run away from you and turn a cast iron stove red, i bet youll reconsider adding more pressure to the crockpot.
quite a few people have had great results with using the pump from a typical becket style furnace gun, coupling it to a DC wiper motor and turning that very slowly with a PWM controller and powersupply off ebay.
simpler and less energy consuming than that, is a stack of minibike tire tubes on a vertical post with their valve stems linked to a common line feeding the top of a sealed grease reservoir. put a weight bench weight ontop the stack and you get your fixed PSI until they all bleed down and you refill with a bike pump. the bleed down can only happen as fast as you burn the oil, which is obviously controlled by a needle valve.

