I took the Hova and its heating element, and added a fish-shipment cooler; wow, they were the same width and I got lucky. I put in a tub; it is very roomy in there, and the tub I used is about a third of the floor-space of a 41-qt tub, and about twice as tall. Pics: the temperature was not yet up to par, since I had just plugged it in, but I put mock substrate into the tub and placed the thermometer probe into it for a better idea..
I used the hova as-was for rat snake eggs last year, and it holds its temperature right-on. I am now testing it to see if it'll work as well with a larger space to heat.