If you ask me, the ambient/cool temps are perfect. When you measured the hot side, did you take the temp directly on the glass underneath the substrate? And did you take the temp outside or inside the hide on the warm side? Just for reference, with my enclosures, the floor temperature inside the cage but outside the hide is around 85, but inside the hides it's closer to 89. It's worth checking both inside and outside the hides.

Aside from adjusting the hot side temp (you want it 88-92) which you only needed to turn up ever so slightly, not all the way like you said you did, your setup sounds fine. The nly other thing I'll add is that a 20gal can be a bit big for a smaller bp like yours, so you may want to grab some fake plants to "clutter" up the cage, and some black construction paper to black out the sides and back of the tank. It'll make him feel more secure.