For many years we have travelled to Gettysburg and totally enjoy it. I drive a 2010 F150 5.4l V8 towing a 25' Sunline, actual loaded weight is around 6,000#.
Pa Turnpike is good for towing Major mountain grades are the Allegheny Mountain and Sideling Hill, and neither will be that bad for your 5.0 V8. I just put it on cruise and let the truck do the work.
Travelling east on the Pa. turnpike I exit the turnpike at exit 201 at Rt. 997, and drive south to Rt. 30, then east into Gettysburg. this route is very driveable with my 25'/truck combo and not alot of traffic.
I would suggest our favorite campground there, being KOA Gettysburg. Yes, its a little pricey, but very well run, definitely worth it. We have stayed at several others in the area, but settled on this one.
Good luck and enjoy yourselves!!!!! Let us know how it goes!!!