Now that I think of it, the Palisades region of the NYS Parks, Recreation, and Historic Preservation, go all the way to Ft. Lee NJ. If they are using a repeater you may want to try those frequencies.
Also, if you do take the drive, I'm sure you won't get in the way. Commuter roads go all through there and basically have public highways. Even the small 2 lane roads have regular traffic all day long.
If you get out of the car and start getting involved, then you may be interfering, but driving through will have a zero impact. I'm sure they are searching in the wooded areas, they may ask you to keep an eye out while driving around. It's a BIG park and another set of eyes out there is not a bad thing.
If you want a good place to receive the frequencies, try Perkins Tower. The views are stunning! You can see the NYC skyline 50 miles away.