I made this post a few days ago, but got no responses. Not sure if no one saw it, or just didn't care (ouch) ...
When I look at the list of National Parks, in order to get 50 in 25 states ( excluding Alaska) you would have to do the following; 1) Hit Yellowstone in all 3 states that it lies in; Wyoming, Idaho and Montana. OR Smoky Mountains in both TN and NC along with Yellowstone OR Death Valley which is in both CA and NV. This is assuming IBR rules allow taking credit for a single park in multiple states. 2) Get Acadia up in Maine, which I assume would be perhaps on the East Coast leg 3) Get Isle Royal in Michigan, which is only accessible by Ferry. This one will take some considerable planning, to catch the ferry on the most efficient schedule during that leg. Yes, this will be very interesting on legs 2 and 3! Smarter folks on here than I can shoot holes in my theory, but me thinks Alaska might have to come into play on Leg 3???