I do not know the temp output but I refer to my small miners as heaters, one more consideration would be the noise produced, and you want two units?
You could always build a vented and soundproofed space, but only tackle this if you have a good hands on know how.
Hmm. what about just using the garage? Think I could still pick up a wifi signal with a range extender?
I would use cable instead of WIFI.