You don't have to sell your Astro after all. Apical Industries, a subsidiary of Dart Helicopter Services (DHS) has recently certified Emergency Float Kits for R44 & R44 II helicopters which can be rerofitted to Astro, Ravens or Clippers. One of the kits includes skid extensions to allow use of standard landing gear. Also, no horizontal stabilizer is required. The kits are FAA and Transport Canada approved under STC SR02049LA. EASA approval is expected soon.
You can go to the DHS website at darthelicopterservices.com and see an Astro on floats on page 83 of the catalog.