Hi Scott,
 about them hot tubs.
If you rub some vinegar around the edge of the water and the edge of the
tarp where the bees enter and use the water.
I know a beekeeper that his wife had horses and the bees would go to the
drinking fountains for them and all they did was use the vinegar.It
worked for them.
If you can setup a bath tub with tap water in it and something floating
in it so the bees will have something to land on.

Have a Blessed Day

Bob Butcher
Tucson Az.