I'm betting if you contact Tropic directly in advance, they will let you know what they can do (and will do their best to help) ...... if it's a last trip, flying over the sea and reef would be a very special sight. There are wheelchairs at International - not sure if there are any in San Pedro. Getting up and down the stairs to the little planes would be the biggest challenge (but their are people and railings ...). Getting into a boat might be at least as chancy if not moreso, and for sure not as comfortable as the back seat of the plane. Bless your heart for making this dream trip happen for Mom.