nice... drivin' on that beach looks fun, just dont get to close to the edge
anyway, as for wheels / tires, yes you *can* go with smaller wheels and larger tires. i know on the current model PF, the bolt hole spacing is a bit wonky, and not many mfrs make wheel packages that fit the spacing. this may or may not be the case with your year PF... but i cant speak with any experience. also, you have to make sure your brakes will clear the wheels. smaller wheels may interfere with the brake calipers... this is bad
hopefully someone with more experience speaks up... until then,
welcome!
~mike