or just let him swim around in a bath for 20 mins or so just prior to shedding if you have issues. if the shed is bad and patchy u could probably do with a little more humidity. 40 or 50% wont cause RI's. you can try using repti bark or something similar as substrate which tends to hold moisture alot better. i use reptibark and my humidty will happily sit on 75% for a few days with a spray down, you wouldnt want that much humidity for your snake though.