The way it's been handled here (at my current employer and my clinical site) is that the buckets are off the floor during mealtimes. If a pt. needs toileting (in this instance, bedbound & incontinent (e.g. wearing briefs)) or requires bathing/linen change/etc. then it can be done, but we bag the contaminated items & put them on top of the wastebasket or in the restroom. Technically, there is some concern with infection control, but since the bagged items don't ever leave the pt's room (at least until the buckets are back on the floor) it tends to be limited to the immediate area (pt. & whatever roomies they have, plus restroom). Also, we get 'em a fresh tray.
It's not an ideal solution, but far better than letting them sit in their bodily wastes until a more appropriate time, no?