i would do this:
get a large chilly bin &/or a few smaller ones to put your fish in, i have just moved & used my 100L chilly bin & a 30L one to transport all my fish. if it doesn't take too long oxygen wont be an issue as long as the fish have enough water but add an airstone if you can.
you don't need to save too much water, just think of it as a large water change. empty the tank cleaning out the old substrate & replace with new substrate. make sure it is well washed as this will save time in making your tank clean & looking good again. i would 1/4 fill the tank with a hose (how big is this tank?) then add some hot water from the tap to bring the temp up somewhere near where it should be, get the filter going if you can with a low water level then add the fish & tip the original water back in. once the temp is near normal fill the remaining space. i have done this in the past week & it worked well & all stock survived the move.