I have  a question on installation of an MRC Sounder decoder.  This is the 1665, a generic steam locomotive sound-only decoder.  The instructions from MRC are rudimentary;  they only state it needs to be wired to railpower.  I have done that.  I need some advice on how to mount the decoder itself.

I put it in a Harry Potter Hogwarts Express for my daughter.  She loves it!  I temporarily stuck the decoder in the cab with a simple Lenz decoder.  I  want a better mount, though.

There is no insulation or heat shrink around the decoder, and it seems to get rather warm. Could I stick it down with some bath tub caulk in the tender, or will that cause damage?

I realize it is not the nicest-sounding or performing decoder in the world, and neither is the loco, but it makes my daughter happy to run "her" train and work on scenery with me.