Big one is to really rinse out the fuel gallery ( ie all the belly panels). Before going into salt, spray the wheel wells and gear actuators with LPS or equivalent. When it gets back home rinse the aircraft, particularly the tail, and the floats with large amount of water and then get in there with soap and brushes. Check float compartments for any water that has leaked in. If you find any remove it and rinse floats. Pull the wheels often and re grease the bearings if you are only going into salt very occasionally I would suggest redoing the bearings after every exposure.
It is a lot of work but if any salt water residue is left it will fester and so it is pay now in labour, or pay a lot later in parts.....
Viking also has a series of SB's covering water operation.