Different states require different things for residency. I have no idea about PA.
I would just go in and do a change of mailing address you can get your mail anywhere. I would not say anything about you physical address and from the searches I did I could not find anything saying you need one in PA for a drivers license.
Most times they will want a physical address for vehicle registrations because of taxes, but was unable to find any codes on it for in the PA dot.
A lot of places you need to uphold your state residency to keep the license. I live in SD because of there laxed residency laws and they will let you do 99.99% of the DMV paper work by internet. SD will also drop your jury duty if you call them with in 30 days of them setting out the letters, a lot of states are very stick about there jury duty.
