Get a tupperware container, place a heater and a PH
or two and place the animals in it.
I would then get some trash cans and siphon them part way with water (to keep them from overflowing when you put the rock in). Then you could place the rock in the cans and continue filling them.
As for the sand,get another container and take out only as much as you need to move the tank and do the switch (I assume this will be a quick changeover) just be sure to keep the sand saturated.
After you are done with the switch place everything but the animals back in. I would suggest running the tank for 12-24 hours and do a good test on the water parameter before returning the livestock. Just to be sure nothing spikes from all this activity.
Good luck dude!!
Oh, if you don't have enough room in the garbage cans for all the rock, be sure to place some soaked towels over any rock you cannot keep submerged.