Getting a multi-engine seaplane rating in a Beech 18 is the only way to go when it comes to a seaplane add on. This aircraft is owned and operated by Sheble Aviation, world leaders in flight training for sea plane ratings. Float plane add-on is one of their many specialties.
She is amazing to fly much less getting a rating in. Expect the best real world flight training for seaplane operations by flying on the Colorado River on the AZ and NV and CA borders area.