It sounds to me like you should tell the band to come prepared and get their act together before you come back to a practice. Double so if this is just a cover band, everyone should show up knowing the parts and if they don't there is no reason to risk anything for them. I hate hate hate unprepared practice, my time is important. If I were in your shoes you bet I would have cancelled because of rain, or just because I felt like watching TV that night. Now, if they start showing up prepared and ready to move forward I might have tried to go for sure, but where I live it often rains at like 4" an hour. Of course I always leave a cab at practice space so I don't have to haul stuff in inclement weather. Amp as well as REDDI are in water tight cases too.
Good luck.
Good luck.
