As a park owner I would not allow the son to be on the lease. It is not because of the DWI but the credit score. If you told me I could have only one measure of a persons character, responsibility and suitability as a tenant it would be the credit score, hands down. I am willing to discuss extenuating circumstance (e.g., medical bills, recent divorce, etc.). A person would have to be trying to get a credit score of 488, that’s about as low as they go.
Greg’s points are dead on, I’d say the odds are better than 50-50 that this guy will be a problem for you, especially if dad moves out. If you should decide to move ahead, discuss with the father and determine how long the son needs to be there (transitioning?) and limit the lease time for the son (3-6 months?) and then its time to move on (you may want to review this with your attorney). One of my biggest red flags is a parent wanting to buy a home for his/her adult children, or co-signing the lease to get them in a place. Rarely ends well. There’s a reason they need parents ongoing enabling. Park owners have enough headaches to deal with, to me this seems like a potential self-inflicted wound waiting to happen. Good luck.