How to position the UTH?

[VenusAndSaturn]

So a few hours ago I just finished setting up my leos 50 gallon bioactive setup.
It has Terra Sahara substrate mixed with spag moss and leaf litter. A few plants, water bowl, hides etc.

Now I originally thought the UTH would be fine underneath and would warm the warm hide to correct temps. However I have found that because it is somewhat farther away from the glass it barely does anything but raise the temp by 5*f. Which is around 80 in total.
I need it to be around 88-95 and I can't position it any other way outside of the tank to reach that hot spot.

My main question is, can I put it inside the tank below the substrate. Of course regulated with a thermostat.
Would this cause any damage to the heat mat at all?

https://www.amazon.com/gp/product/B018VQ72RI/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
This is the UTH I'm currently using.

 

[KeyBlu422]

Personally, I wouldn't risk it. Maybe try placing a tile where the UTH is to create a slightly warmer area than the rest of the tank. Also, 50 gallons?! That's enormous for a single leopard gecko, how much room do you have where you hold all your reptiles?

 

[VenusAndSaturn]

I'll see if I can get any tile either tomorrow or sometime this weekend,hopefully that will work.
Currently she just has a 50 watt CHE over her cork bark making a warm/basking spot of 90-95, but I feel like a UTH would be best so she can stay somewhere dark and warm during the day, she's not a fan of the light because of her genetics so I doubt she'd use the warm basking area during the morning at all or in the late afternoons when the lights are on at least.

I like giving my animals a lot of space, of course as long as they can handle it and dont get stressed out by it.
I keep all my animals in my room, which i have only my bed as my main living space and then a small 4x5' walk space surrounded by tanks. And soon I'm getting rid of my bed to make space for my tegus enclosure. So I'll end up sleeping either on the floor or a couch which I prefer either or compared to a bed.
Which may seem weird that a person would basically give up so much room for reptiles in their own bedroom but I prefer it like this.