I agree with @Bsch4477......... probably best to leave it as is since you have a will. Two things:
1) Any transfer from you to your son would involve drafting a deed, recording, etc. which may trigger the due on sale clause in your mortgage and, regardless, would involve the services of an attorney (so figure $1k as a floor, which is not worth it at these values).
2) With respect to your loss, I can only assume it is likely very, very small considering your son covers all of the expenses and the annual depreciation deduction is rather low (based on $90k, approximately $3272/yr). At those rates, the IRS is not likely to scrutinize your return, particularly since your "small loss" would be a passive loss.
