For the OP, one comment regarding towing a trailer: Don’t be tempted to use I-70 between Frederick and Hagerstown, especially coming eastbound if you’re towing a trailer on your way back north. That segment has a lot of accidents near South Mountain and there are a fair number involving trucks. If you come through Maryland, I’d suggest you take US-340 southwest from Frederick to Charles Town, then WV-9 to Martinsburg.
I have a work colleague who lives in the Catskills during weeks when she telecommutes, and she regularly visits her mother in the Martinsburg area. I’d be happy to ask her what route she likes if you want, though it’ll be Tuesday before I get to ask her due to the holiday tomorrow.