We're going even later than you - will be there Nov 2! And of course most of the Acadia Visitor Centers, etc, close October 31. You'd think with close to 5000 people coming in, they'd stay open for the extra two days, but I guess they just have to pick a date and stick to it.
If I'm reading the Acadia National Park website correctly, ride share drivers can do pick ups and drop offs, but cannot provide tours. So it sounds like they'd be okay for what you're looking for?
Interested to see what other suggestions you get - I've seen other people recommend renting an Acadia GEM (electric vehicle) or hiring AtYourService on other threads, but they both seem a bit high for me so I'm still trying to explore options.