That sounds like an awesome idea!
The idea I had for the rewards that if you succeed on a roll they could count as an "additional success", so if the GM rolls a 2 on the event level meaning you need 2 successes to overcome the challenge, and you succeed using that item, you get 2 successes instead of 1 success.
And for the ending I imagined it kinda goes as long as you want it to. Whenever you're done for the evening or you hit the time that you set for the session, the next location would be The Capitol, concluding your journey. But honestly you could always set it as "it'll take x amount of locations to arrive"
Thank you for checking it out!