Jim,
Can't say for sure regarding the room constraints. The UDC in the attached photo (from the HL Cyclone Gallery) is identical to mine.
Is the inlet at the bottom - left, the Black tank flush inlet? I was thinking of drilling my access hole just below this inlet but above the cargo bay's floor level (silver edging strip - left side of UDC photo).
Now that you say they are already mounted in some of the the other units, I'll have to find one and scope it out. Better yet, I'm taking the old girl in for warranty and service work this weekend. I'll "ask" the techs if it is possible since they have to repair my still leaking shower drain and may end up pulling that cargo bay panel anyway.....