The only thing I see in what you listed as having on hand that could most potentially lead to habit formation is the diazepam. That stuff can really be a godsend for withdrawals but don't dose too high, you don't want a spike in tolerance in that department at this time, just enough to keep the symptoms that a benzo works on away. The zopiclone can be habit forming in some people but it isn't as likely as the valium by a decent margin as a lot of people cant really get much enjoyment out of it and just fall asleep. I would go from diazepam then step down to the zopiclone maybe? Then down into the less serious stuff. I guess you could use the prometh and valerian where needed or as the next step after the zopiclone. Basically I would use the strongest medication to ward off the most acute symptoms and then move down the order of available substances as the WDs become less acute, you don't want to be getting just as zonked in a few days when the withdrawal isnt as bad as it is one the first day or two of acute symptoms.
It is understandable to be worried about picking up another habit of use But I am guessing the kratom has been in use for a decent while, so it would sure take some time to get to that level of use with another substance, so just watch out for that. The meds shouldnt be used to try to get through the withdrawals with zero discomort because if that is the goal that is how a new habit forms, so just be circumspect and understand that you should be using other substances to make withdrawals bearable not un-noticable. Not that you shouldn't make up your own mind on how to navigate your symptoms but it just seems pretty darn unfun to undego without anything to dull the edge.
Someone else has already mentioned loperamide. That stuff does help a lot, And I always just forced myself to do whatever physical excercise I could manage to do even if it was really unpleasant or painful as at least then I was sort of in control of the discomfort instead of just laying/sitting there and having it come at me, it does offer a bit of relief afterwards. I've never had very terrible opi withdraws, just the ones you get at the end of a decent binges.