I've spoken to Uber drivers who have done 2-3 hour rides before, but I think most drivers would refuse it, as it's difficult to get fares coming back the other direction (I believe the driver app has some ability for the driver to specify the direction (s)he wants to go, but I don't know if a Maryland driver would be able to pick up rides in Pennsylvania) and Uber's pricing is so low now that the driver could easily end up losing money if (s)he has to return empty.
If you do it, I'd immediately call your driver when you're matched to tell him/her your plan and offer to cancel if (s)he doesn't want to do it, so you aren't hurting his/her acceptance rate by forcing him/her to cancel. My guess is if you give it a few tries, you'll eventually get somebody willing to do it.