You don't have a bus yet, right?
Maybe, shop for a longer bus. Our skoolie is 42'2". Add a rack to the bumper and I max out at 45 feet.
You might consider pulling a trailer behind your conversion. Either RV living space or enclosed storage. Some members here have added slide outs to the rear and sides.
We already had a shipping container and an rv when we added a school bus to our yard. I recommend having onsite storage and restroom facilities before you begin your conversion.
"If there is no struggle, there is no progress."