I don't mind, and I also don't want keepers to think that only a UTH is enough, though it might be...as I tried to explain, it all depends...each set-up is different.
Using UTH, you ALWAYS need part of the enclosure that has NO heat, for safe thermo-regulation by the occupant...but for a colder room or a reptile that needs
to be warmer, you might need to increase the ratio of UTH : cage floor.

FYI- My home thermostat (& therefore ambient room temps.) is set to 70* winter & 80* summer. I have an Aussie Spotted python & desert rosy boa that prefer
the warmest temps, but you're correct- most of my snakes now are colubrids. (including 4 large Florida rat snakes that also like a fair amount of warmth, but still
not like BPs) FYI- when I had a large BCI, she was kept in a huge glass tank, with about 2/3 of the floor heated with 11" wide UTH (Flexwatt), and in winter I put
a towel over part of the screen top and with an over-head warming light used for her basking. So it all comes down to the variables. (her tank was insulated too)

All of this is why we all recommend setting up & trying out cages & equipment for at least a week prior to reptile arrival...so there's time to tweak or even buy some
additional stuff as needed. It goes without saying that the larger cages have more air space to heat up than smaller ones do.

About your tubs: I've seen racks that have open sides, and some that are enclosed...that alone could make a huge difference.