Hotels are usually agreeable to short term parking as long as you book a night there. If the tour is circle tour with same start end point this would work. it is a better option than a shopping center or other parking where your car will stand out as a lone magnet to theives, burglars and police at 2am.
Option two, drive to Hershey, sell the car, do the tour, buy new car ,drive home. This way you get a worry free tour and a new car!!!!!!!
OK, we're back to option one.
For future ref, in cities, LT airport parking is a good option. Though, not the cheapest way to go.