My son took out a loan and forged my signature as cosigner, do I have any recourse without going after him criminally?

No, you don't have any recourse against the lender--they are not under an obligation to perform verifications of the information, and are entitled to rely on the materials they are sent. Your only recourse to get out of the loan would be to let the vendor know that you son forged your name, which means holding your son out as having committed fraud. If you have the wherewithal to pay off the loan, you might instead pay it off, then sue your son for the money he owes you from your paying the loan. That might put a civil judgement over your son's head, but not criminal liability.