Been wondering what the outcome was. Hope this works out.
To answer your question. Assuming the last hurricane did not pound the hull into something hard, the hull is probably sound enough to survive a pull out of the marsh and a gentle tow back to a dock somewhere. Once the boat is floating be sure to check for leaks, especially at the keel/hull joint. Then get it hauled out and go over the hull and sound it looking for delimitation. You might find a friendly surveyor to help you out on this, but it will add cost. A knowledgeable friend may also help.
Grampians are built like the proverbial brick outhouse, that's in your favor.
Good luck!