First off, you can hot glue the probes. That's what I do and it works like a charm. Also easily removable.
If you can afford it and wouldn't mind the heat, I'd definitely get a space heater to just heat the room to 77-78*.
As for the temps in your cage... I highly doubt 99* is hot enough to burn a snake. Think about it, you can touch the hottest part of your body (not specifying where that may be) and you won't get burned, or even feel uncomfortable (damn, I'm really going too far with this
).