We stayed at Artillery Ridge campground in Gettysburg a few years ago and liked the campground. They have trail rides into the battleground you can go on from the campground - bring your own horse (they have stables on site, very cool!) or use a horse from the campground. They used to have a huge diorama at the campground that was impressive with a light and sound show, but I understand that it may have been moved to a larger building.
Get one of the "self-guided" car tour CDs. Any campground there probably sells them. Makes for a very relaxed tour of an incredible battlefield. If I understand correctly, there are monuments to fallen soldiers from every state all over the battlefield. We found monuments to Connecticut soldiers -- made it a unique tour of the battlefield, looking for specific monuments.
Also agree with watching the "Gettysburg" movie beforehand.
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2021 F150 2.7
2004 21' Forest River Surveyor