Boa tub heating

[Ba_sands]

Yes I’m new here, I have a 5 month old hypo boa. So my issue is heating now that it’s getting colder where I live. I had her in a glass tank this summer and everything was good untill it got cold. I tried everything and couldn’t keep the temp and humidity both up so she was moved to a tub a few days ago. She’s still settling in good it seems but my temps are lower than they should be. I have a uth on 1/3 of the bottom of the tub(3 1/2x 1 1/2x 1). The thermostat is under the bedding in the tank at 89 degrees. I’m mainly having trouble with the air temps only being mid 70s on the warm side and 71ish on the cool side. The humidity is also kind of high but Her water is half on the uth so it will be moved. So after reading everything I can find I would really not like to run my house that warm all winter. I was thinking of putting another uth and a thermostat on the cool side, maybe set at 78ish to raise the temp on that side and maybe the ambient of the hole tub. I’ve also moved the tub into the warmest room in my house. May have to down size water bowl as well. I got a shallow tub to hold heat better. My house is cold and winter isn’t even all the way here yet. It’s an older house and poorly insulated. Any help would be great. I also have a heating ceramic light and a thermostat but I wasn’t sure how to safely screen the tub lid for the heat.