Thanks for all the info at least now I have a better understanding of what's required. Think I'll leave this endeavor for now, don't have any money to spare for gear for at least another 6 month. Damn residence tax came in this month, gonna be poor for a while.
How do you intend to share your images, or view them? Online? If so... there is nothing wrong with cropping. Don't worry about it and enjoy a nice clear night when you get one.
I wouldn't share them if they're heavily cropped. If I did get a half decent one it would prob end up on flickr or 500px.