Hi all, I'm moving some of my larger snakes to PVC cages and I've been struggling to heat them properly. I haven't moved my snakes into their respective cages because of this. The room in which they are housed has an ambient temperature of around 70-75 degrees. Currently, I have a herpstat 2 and a 11 x 23 UTH from reptile basics. The PVC has a recessed base to use a UTH, but I can can't get very much heat to transfer through the PVC. There is no substrate in the cage either. Any tips would be greatly appreciated. I'd like to avoid having to buy an RHP, but it is looking more and more necessary.

P.S. Where should I mount my probe? Currently I have it mounted between the UTH and the enclosure.