You are proposing that the player cover his clothes from head to toe in horrific flesh-melting lye, wear those clothes through some miraculous act of contortion, then carry out his daily activities without the paste seeping through and burning him, without getting sweaty or wet in any sort of way, all on the off chance of being caught in an acid rain shower, where, assuming you’ve somehow slathered on enough to protect you from several minutes worth of an acid deluge, the basic powder reacts with the acid and loses its effectiveness, meaning you have to go through that whole process all over again.
This is a more realistic scenario to mitigate acid rain than carrying a waterproof shelter around.