I agree. Instead of sending demand letters directly to the open-source developers, wouldn't it be more efficient (and more compliant with the DMCA) to send the demand letter to Github? If the developers are truly at fault, they will have breached the Github terms of service and Github will have a cause of action against the developers.
Best 80/20 solution is to form an LLC in your state through legalzoom.com. Actual incorporation (i.e., forming a corporation, usually in Delaware) is usually only necessary once you're ready for equity investment.