Where is the ambient air temps measured with and location? Typically when people say this they are measuring under the RHP this is not measuring air temps in this case but the surface of the probe being heated by the RHP. To measure then place it at least 6 inches away from the RHP middle height of the enclosure and suspended from the ceiling. The last person whom said exactly this found the with no lights running at all (1 hour after they were shut down) the air temp was 3º over the room about the same as I found in my test enclosure. She found that the lights made the temp difference not the RHP. Try it.
The thought that placing a UTH on the enclosure and it not heating the air then turning the enclosure up side down and it suddenly heating the air is crazy. This is all a RHP is a carbon element in a box. No different than flexwatt on the bottom of a PVC enclosure if you use ABS enclosures and thin walled it is the same.
The thing that really is concerning is where is the probe placed. I do not believe a snake should under any circumstances be able to come between a heat source and probe. All my tests the only probe placement that works is dangling from the panel but it is kinda sketchy. I have two RB 40w RHPs one I tested in a 12 inch PVCx enclosure (no snake) for 3 months. When I ran a full power test I hit 150º on the (1/4 inch thick) substrate. This is as hot as my UTH get. Too hot by far. The arboreal set up (26 inches) the floor never gets over 80º there is always escape for the snake from a burn. IMO they should not be used in heights less than 18 inches as they can easily over heat the floor in shorter enclosures.