There are at least a few people on this forum who have rented a bike in Maui for that ride... you may want to bring your own saddle & pedals but yeah, rent a triple.

Do some digging/posting to see who's already done it that can share some advice with you.

Saying the overall grade is the same is nice, but... 36 miles with no let up is a different kettle of tea. hopefully you can convince the family to drive up in the afternoon or do occasional sag for you. That road is definitely on my bucket list.