The UTH shouldn't keep the ambient temp up at all, it's only function is to create belly heat. If your air temp on the hot side is 88-92 then the surface temp will likely be way too high. You need to find out the surface temp of the tub over the UTH, as measured with a temp gun or IR thermometer.
You need a gram scale so you can weigh the snake and the feeders - there have been reports that a few sellers regularly ship feeders on the lower end of the low/high weight - and you need a temp gun or IR thermometer so you can get an accurate surface temp.