Thanks for writing. That's a tough situation as a large number of salt-tolerant plants don't like to be in standing water for extended periods of time.
Your best bet, I think, is to contact your county extension office --- the agents there should be more familiar with plants indigenous to wet seaside areas than I can be.
Sorry I can't help more. I'm sure your county extension agent will. Good luck!
---Justin, Senior Garden Editor, BHG.com