Problems with tub

[raisinjelly]

Hey guys! I'm going to be taking in a couple of rescue BPs to foster. Earlier last week I had been thinking I wanted to go with tub setups for convenience but I wasn't sure if that was viable outside of a heated reptile room. However, when I asked about that on a different forum I was assured by a group of different people that the UTH would easily bump up the ambient heat inside the cage. So I went ahead and bought all the supplies, and the tubs have now been up and running for two days (sans snakes) but well... there are indeed problems.

Setups - Both are hooked up to a Herpstat 2. The probes are sandwiched between the pad and bottom outside of the tub, and the pads are taped along the edges with heat resistent tape. Each tub has one line of airholes around the outside, spaced about an inch apart.
Larger tub: 44 L x 19 W x 6 T with 11x17' Ultratherm pad fit length-wise.
Smaller tub: 21 L x 15 W x 6 T with 6x11' Ultratherm pad fit width-wise.

As for the problems, well for one the temps inside of each tub are not being affected by the UTH like I was led to believe. Like, at all. It's a tad bit warmer an inch or so away from the pad but the rest of the tub is straight up room temperature, which is 71-73F. Was I seriously given wrong information by no less than 5 different people? I specifically asked if a tub setup could be used outside of a specially heated room and mentioned that I was under the impression that UTH's did not effect anything but the surface temp right above them, but was told that wasn't the case. Well...apparently I was right after all, or am I doing something wrong?

Secondly, the heating pads themselves have very inconsistent temps over the heated surface. Even the little 6x11' one could be like 81 degrees in one patch, 90 degrees an inch or two away, and 93 degrees in the diagonal corner. That's a range of up to 12 degrees over a 6'11 inch surface! The larger one is worse.

The humidity is doing good (a little too good actually) in the smaller cage but not quite up to scratch in the larger cage, and I have a very large bowl in there. I've tried moving it closer to the heating pad already but it doesn't seem to have much effect, maybe due to the low temps?

As a bonus suck, neither of the two Acu-rite temp/humidity gauges I spent $18 on each is at all accurate. One probe that I have set on the hot spot is reading 78 degrees, but measuring in the same spot with a heat gun says it's 90 degrees. That's 12 degrees off. :/

Just...ugh. What do? I'm so frustrated