I know 85 is recommended but What about 90 degrees along with a cooler side of the tank
If is a bit high, should be fine though, if the scorpion can easily move to the cooler side of the tank. You should aim for about a 10 degree difference between the hot and cool side, and preferably have a couple of different hides in different areas so it can choose an optimal temp.
There are basically 2 optimal ways to heat a forest scorp tank: IR bulb angled to only hit half the substrate, or reptile heat pad stuck to the outside of the glass on the back wall, so the bottom of the pad meets the top of the substrate. I prefer the latter method but either should be fine. The only method you should never use is a heat source below the substrate, because they'll try to burrow to cool off.
