With the tubs I use, the heat tape covers between 1/4 and 1/3 of the tub (which is the recommended min/max amount of hot spot) and it does a great job of warming up the hot spot to 89-90 degrees, and some of the residual heat does slightly transfer to a warmer ambient on the warm side.

The cool side of the tubs are more dependent on room temp, but I'm able to change the amount of airflow in the house via the vents. So most of my house is a comfortable 70-72 while my office/reptile room is closer to 78-80 year round.

It's definitely not a perfect solution, but it can also be accomplished with a cool side strip of heat tape, but it again would need a second thermostat or a thermostat with 2 probes and 2 outputs. Which they do make, but are way more expensive than 2 of the Jumpstart Amazon thermostats.

If you decide that more than 2-3 snakes is the plan for you, a rack with either a warmer room or 2 t-stats is definitely the way I'd go. It simplifies keeping snakes a lot, but be warned, if you build a rack with a decent amount of tubs in it, you'll end up trying to find ways to fill them. Lol.

And as for multiple probe/multiple output t-stats, I'd recommend the Herpstat line of thermostats by Spyder Robotics. They have t-stats with 1,2,4, and 6 probes and outputs. Plus they have the benefit of not being an on/off t-stat so they keep a more consistent temp overall.