I think that you should (rethink) the idea.
If your determined to launch at that spot, why not just launch it and then drag it back out when finished and just flip it over?
Anyway launching is only one part of the whole equaission.
You still need to be able to get in and out of the thing.
And for that a Kayack or a canoe would be a better choice.
Consider launching from your seawall, maybe install a roller on top of it.
Getting in and out of it might be easier.