I have no personal beef here because I haven't visited the park since the rise of The Rise, but I question the logic of boarding passes. I know there is the risk of disappointment in my suggestion, but I think there's that risk with any solution for this seemingly not yet ready for the masses ride.
Why not allow standby only? I know you FP fans will hate this idea, but just go with me on this one. If you're considering getting into line when the wait time posted says "5 hrs wait from this spot" and you're willing to get on, then that 5 hrs out of your vacation/visit is worth the ride. I assume the line will cap out with most people unwilling to wait an entire day for one ride, so let's say it caps out at 3 or 4 hours where no one else will get in line for those wait times. Once the wait time becomes longer than the hours to closing of the park, you cut the line off with no more riders. Anyone in line before cutoff is guaranteed to ride assuming their isn't a ride breakdown. If there is a breakdown that can't be fixed timely, everyone in line is given "special" FP for Rise. Assuming someone will figure out a way to make and sell these FP at some point, the paper used will have Mickey Mouse hair embedded in the paper to prevent counterfeit tickets from being created.
IMO, if you're willing to wait in that line, you're happy just to be guaranteed a ride. You're also sucking a huge group of people away from other ride lines allowing other guests to get on their rides quicker. And no one-person line holding for a large group either. In this case unless you traveled from far away and are leaving the next morning, you're guaranteed a ride if you really want to wait.