Depending on what your tub will be sitting on you can just tape the flexwatt down to it with the special tape they sell for this (alumium tape I think it's called...I suck at these details lol...but Reptile Basics sells the stuff). Then your tub just sits on top of the flexwatt which is controlled by a rheostat or tstat (tstat is better). Your only concern really is what the flex sits on. If it was a wood dresser for instance I'd likely put a spare melamine shelf (like from a bookcase) on top to protect the wood finish. Melamine is used to construct snake racks so it's perfectly safe with flexwatt that's properly controlled. Then when your baby graduated up to another tub size, just set the new tub down on the flex, adjust and check temps and you are all set. With a small baby tub you shouldn't need to worry about dual flexwatt...it's a small space to warm up really and you do want a proper temp gradient end to end for the snake to utilize.