I poked around on Allstays app and there's an RV service place in White Haven, just west of the speedway on I-80. It doesn't say if they have a dump station, but my guess is they do. Maybe worth a call.
There's also a Pilot north on I-476. They may have a dump station.
In a pinch (an you're probably headed east) there's a KOA in E.Stroudburg. I've spent a night there. It's a KOA.
Jerry & Jeanne
1996 Safari Sahara 3530 - 'White Tiger'
CAT 3126/Allison 6 speed/Magnum Chassis
2014 Equinox AWD / Blue Ox