i tried something similiar to that, i would do the rowasa at night and then an hour before i got up i would either do another rowasa or a hydrocort. it did not help, in fact i found it was so much liquid and it wasnt absorbing well and i was all liquidy bowels that day.
that being said, ive gotten out of my other flares by doing a rowasa at night and then doing 2-3 canasa supps during the day.
however, ymmv, so its def worth a shot for you to try on your own