""... temporary platform in one night? ... ""
Didn't the Boston Elevated Railway build temporary high platforms in the Tremont St. Subway, 120 odd years ago? Then, in a weekend, filled in the platform gaps the Green Line stopped using on Friday and reconnected the tracks so the then Orange Line would run through there starting Monday?
And in 1908, the Orange line stopped running through the Tremont St. subway on a Friday, then overnight enough of the high platforms cut down so everyone would take the Green Line through downtown. They would connect with the Orange Line at North Station and at Pleasant St. (near Wang Theater) for one weekend. On Monday morning the present day Orange Line from North Station to a little past Chinatown opened. (That weekend through Orange Line passengers could also take the North South Rail Link over Atlantic Ave which connected to Dover St. to complete the ride to Nubian Sq.)
School bus drivers require additional and unique qualifications. If the Boston school department supplied bus captains or chaperones to meet still more school bus requirements, it would be easier to find drivers who have the needed driving skills.
Build something. Anything.