Since they are not licensed by the health dept. all you need is the facilities to hang, butcher and store the deer till its picked up. That coupled with being able to butcher a deer rather quickly, some money to purchase neccessary equipment, ie. knives.band saws.grinders,walkin freezer, wrapping machine, and bussiness cards. Knowledge on how to make sausage. Once you acquired this then just advertise in your local paper,hunting rule book and sport shops, Word of mouth will spread if your good. Then when you get too busy you can hire some cutters. Good Luck and watch those fingers.
PS I believe the only problem you may run into is the zoning, since this is a bussiness you can' t do it in a residents thats not zoned bussiness or commercial. Also you' ll have to come up with a satisfactory way to get rid of the bones and hides by hiring an outside carting co. The town is not responsible for commercial waste. Once again good luck.