It was certainly a challenge for me iso3200 is probably right, I wasnt concerned with noise, I'd found from home I had no line of site to possible get it and never thought I'd have a chance. But someone offered me transport for an outing and we found a property gate back from a road in a rural area with little traffic and clear enough view. m31 transits at 13deg for me so to me it was my one and only chance for it, so i used worse settings than I normally do just in the hope of getting anything at all! I found the location using google street view, just looking outside of town across paddocks making sure clear of hills and trees. I've sounded him out about maybe another trip this year and I'll be using my regular settings plus the camera now has a light pollution filter installed . only problem is its a decent dark site for me and there is a whole sky of stuff i can get better shots of from there, its so distracting and hard to stay on mission. more cameras i suspect is the answer.
Yeah I need a better computer or several as I use tons of shots to help make up for not being able to use a tracking system, my main computer and laptop at home are both chugging away on data right now. I'm constantly testing the limits of my gear, software and skills in pursuit of a better image result in the end
never stop learning.
Good hunting!