yes, you can get it at loses... no I wouldn't glue it. nails or screws would be much better.
So the probe is attached to the 11" flexwatt correct?
if so you could try putting the helix's probe into one of the tubs (set the Helix to 90) and see if the flexwatt is even capable of heating the tub. back heat is hard even in warmer rooms. belly heat is far more efficient at transferring heat.