48 water bottles might be a little excessive, expecialy if you got 2 -11" pieces of flexwatt... if your tubs are sealed, id guess that they would retain the heat until the flexwatt cought up.... this might also allow you a little more tub space..
easy experiment,,,,,, open the door for 3 minuets, close it, and see how long it takes the stat to regain temps in the tub, and in the incubator temps ,,, then take out ALL the bottles, let incubator stabalize,, and then copy the first experiment.. im kinda doubting that your gonna loose any temp in the tubs.. PIMP bator BTW!
spooky