i like it. i personally think that housing them together sounds fine; i have a T.s.parietalis and it doesn't get much more northern than that. i would go as far as to say that housing different genders of the two snakes would also be fine. they can't mate, they're from different genera. i could see a male putting the moves on the female, but nothing would come of it. the possible downsides would be the male not eating (they sound like they tend not to once they're in the mood), frustration and a need for sex counseling. if they don't eat each other, don't mate with each other, eat the same things and like the same environment it actually sounds like a non-breeder's dream. pathogens are another possibility. go cb.

that being said, i personally would not house two different genders together just because of the way females can put a male off feeding.