First off what smoke pump do you have?

Secondly i would think restricting the flow will only put more stress on the motor of the pump which will only lead to burning up the motor faster.

Third if you could put a speed control inline with the motor of the pump then you could adjust for the amount of smoke fluid that way. Slow the pump down for less fluid flow. speed it up for more.
program it to a knob on your radio so you can fine tune it. I'm just thinking this out as i type. Lol!!!