I bought parcel of property at Pennsylvania private upset tax sale that has 3 rundown campers on it. The campers are taxed. Can I legally sell the campers and have them moved from property?

Camping trailers are personal property, not real estate.

They will have title's and taxes on them, (like cars)
The owners of them will be listed where the tags and titles are done.

You will have to notify the owners of them, and allow them a chance to claim them.