Peuce...ignorance excused.
At places like Hamo and Shute Harbour, there are specially made stairs that you wheel up to the side of the floats. With the caravan it is more often than not you use the cargo door for loading rather than the air stairs. The beaver it doesn't really matter. The doors where designed to get 44 gallon drums in and out so passengers aren't to much of a problem.
The Amphibs are quite impressive to taxi around however, especially going eye to eye with 737 pilots.