Consensus seems to be that you load up one location with as many boons as possible, while closing other locations one by one via emptying them out. When you get to the end of the scenario you head to the location that has the most cards, thus giving you the best chance at an early close.
To be honest, I've played this scenario once. I used this strategy, and it would have been successful had I not had some atrocious rolls down the stretch. Because of my limited schedule, I decided to just take the reward and move on rather than spend time replaying a scenario that I wasn't particularly a fan of.