Sounds like a great trip!!
Yes I think you’re right on track with the Ultra-MTB Race Prep Plan and repeating it twice.
I would suggest taking a recovery week (3-4 days off and 2-3 easy/fun rides, within one week) the week after finishing Base Builder. This will refresh you mentally & physically.
Then plug in the Race Prep Plan and work towards your B+ event. Sounds like that will line up just about right?
Then take another recovery week (as mentioned above the week after that event).
Then plug in the Race Prep a second time with it ending on your Hut Trip start date. That should have you building plenty of endurance while maintaining all your higher intensity aerobic gains all summer long!!
Thanks for the question.