Only housing worth using with the Alexa is the Hydroflex. Peter Romano does not sell but rent his housing plus crew.
The other option is ..... two guesses. Moi. I have a custom made housing for pool work with my business associates.
Red Epic could go up to 22+ stop with Photomatrix. see this link:
Looks a bit strange for me.
Sorry. Back on topic.
In an aluminium housing in the tropics there is little to worry about the 1DC.
All the cinema cameras heats up including my Epic "hair dryer". Just be sure that no tiny splashes or droplets are left inside when changing card or battery. Also the o-ring need to be wicked dry before closing especially if a vacuum system is used (highly recommended).