David,
I thought it was spam when I got a request from someone pretending to be you asking me to join twitter last week. I guess it was a real request now.
Well if you park most of your caravan at Bill's shop, you can park your car in my garage.
I might be able to join you on your way to Harrisburg depending on when you are going. I don't know anything about contacting the media, hotels, etc. in Harrisburg.
It might be worthwhile to stop in Philadelphia as well as Harrisburg, since Philly is where the country started with the Declaration of Independence, etc. (and it is also much closer to my house than Harrisburg).