Phrag pearcei -
IOSPE PHOTOS - would be temp tolerant. There are also some species Masdevallia that are temp tolerant, from low altitude ranges in the wild:
M. anfracta -
IOSPE PHOTOS (this says they are cool to cold growing but then give the altitude starting at 800 m, which is anything but cool or cold)
M. lata -
IOSPE PHOTOS
M. norae -
IOSPE PHOTOS
M. tonduzii -
IOSPE PHOTOS
Although they enjoy warm days, they would probably still like a significant drop in temp over night.
Before you said the temperatures were warm, I was going to suggest Telipogon (see:
http://www.orchidspecies.com/orphotdir/telibutcheri.jpg) as they are some of the smallest, and are one of the wettest growing orchids I know of. If you could keep the daytime temps in the 70s they would thrive in the conditions you describe with water constantly running around their roots.
Let us know what you end up picking!