[mark]

Would something like this work?
-setup a tub with some tank water and LR (ideally from a ich-free system) and bio-balls and run it for a bit with nothing else in it than a heater and circulation to establish the bacteria
-after the first tub has sat for a while, remove everything from your display into tubs and sterilize DT, sump and plumbing (use bleach etc. then rinse).
-add the bio-balls and some water from the first tub to the display and the fish only (acclmitize), also the new dry base rock you mentioned. LR into the second tub.
-run the display hypo for the 6-8 weeks, keep the coral and LR going in the tubs using lights from DT (fish don't need that much).
-at end QT period raise salinity, and the LR and corals back to display.

Sort of the same you're planning. Chance to clean the system really well, then fish have the room of the display for the QT period. The hypo period doesn't effect the LR or corals.