When I was messing around with my RHP I had it set up with the herpstat probe dangling about an inch down from the center.
It got well over 160F on the surface of the RHP (Confirmed by the other herpstat probe and a temp gun) This was while the probe controlling it was set to only 90F. Never quite figured that one out. I mean it makes sense the surface would be hotter than the probe an inch below reads but still...
I just use Flexwatt with my T8, it comes with the groove for 11" tape and a slot for a probe.