I'm probably slightly north of you in 5b. I've planted my potatoes in early March (if I'm lucky), or mid April-late May (if I'm not lucky with weather).
As long as you can get about 90 days of good growing weather you will probably be OK. Not sure how the warm ground might affect them, but I've had some years I've planted pretty late. If you don't have a lot of expense to do so, I'd try it!!
Good luck and keep us posted.
