You don't need to keep the room at 80*....I'd set it to come on about 86-87*, since (as I recall) that's where some breeders keep their ambient room temp. for BPs.
I think 90* is too close to the line for safety...and IF you happened to have a power failure (not rare in heat waves) then they COULD be harmed by over-heating...
you'd have no 'wiggle-room'.