Firecap lets you take a dark frame and subtract it from the light frames. Even with that I haven't been happy with anything past about 10 seconds exposure with the ASI120mc. You might target brighter objects like globular clusters, those seem to turn out OK with shorter exposures.
You might also try those small, round gel freezer packs that they sell for kids lunch boxes. One of those rubber banded to the back of the camera might help. You might want to get a clear 1 1/4 filter to screw into the nose to help keep condensation off the sensor. A filter is not a bad idea anyway, just to keep the sensor clean. If you go with the freezer pack, I would use the one with the cookie monster face purely for aesthetic reasons
ROFL!! I just happen to have a couple of those under my bed, AH HAAA, Don't tell no one K.. Heck I had no clue you could even do something like that, I may try it. Last night I took a 50 frame of the dumbbell, then 50 dark's, capped the scope and all, but the stacking programs don't seem to recognize em..?? Got me. Keep on trying I guess, of course the moon didn't help much either. As for firecap, I can't even get the target on the screen without bumping up the exposure. Dark's didn't seem to work with that either. Live & learn, guess that's part of the whole process. Cookie monster rocks!!!