On a side note, my first RHPs were from Pro Products. Speaking to Bob from Pro Products, he had recommended placing the probe on the cool side (as anyone who's spoken to him probably knows), and setting the thermostat to the cool side temps. I realize some keepers do not like this method, and maybe even it doesn't work well for them. I'm sure the size of the enclosure matters as well. However... that's how I have all my enclosures setup now. When setting up a new enclosure, I ALWAYS set it all up with the RHP installed, then I have about 6 different thermometers with the wired probes, and I place the probes all over the enclosure to get temp readings of all the areas. I place the RHP probe where I think might work (I always start with the cool side placement). I just tape all the probes down, since there are no animals in there, and its just for testing. I set the thermostat (I use the Herpstat controllers) and I give it at least 24 hours. I then take the the readings (I double-check temps using the infrared laser thermometers). I do some tweaking here and there, wait more time, and when I am finally happy with the correct readings I will place the permanently place the probe. In my case, it has always worked out for me to place the probe on the cool side.
All my current snakes are terrestrial, for the most part, and in low-height enclosures. On an arboreal setup, this might not work. BUT... you should do the same thing with a few temp probes and get readings, and tweak, until you get what you need. Easier to do it when there's no animal in there.