I'm saying use common sense when using the hot hands.
I.E put in a cloth sack and put on one side of the tank. Put them in a concealed cardboard box. A snake is not going to make a B line to them and coil around it. Give them some credit, snakes are not stupid.

Again, use common sense! I only threw the idea out. Build upon it! There are ways to provide heat without it causing increase worry for burns.

If you don't want to worry, go buy a generator! Too Expensive? Then save up for one, for future. A lot less worry for something so simple.

I hope you the best in what you come up with!