I'm disabled. Bowel & Bladder incontinent. My various medications as well as my health issues. Cause my bowels to often be very loose. The overnight style adult diapers with a booster pad insert are your best bet. Tranquility ATN, Secure X plus. Its a good idea to sleep on a incontinence pad as well. Even with your better briefs a bad episode of diarrhea can mean a messy leak. I have heard of others using rubber pants even. But I'm in a nursing home and they don't use those.
I realy do not knowe. I have "only" wetting problems but I guess that all all-in-one briefs with tapes will work, look for Tena, Mollicare or Attends.
Hope you will find a solution