As a possible compromise meeting both your key concern and Krivohan's, is it possible to limit the warrior-class-preps and yet allow them to stuff them into their packs?

It's a real hard decision to make when you only have inventory space for 3 or so limited one-shot preps with sub-10-hour durations, getting new ones takes ~20 minutes or more, and yet you have to suck up at least one of them to take on the annihilating paladin. Not being able to stuff them into a container is the real kicker.