[*] Knock on the side of the hull of another boat at anchor
This is the one that having SL may effect. But it doesn't matter if YOU have it as it is a boat pack thing.
I feel you should just get the SL. All the things you worry about far as SL is either in, or not in, your control. You can look at it as a tool and it is normally better to have a tool that you use once in a while than to not have it.