Joe, I went a little simpler. I mounted a remote switch in the engine box which I always used or starting if the boat had been sitting, when cruising rarely.
The switch was wired directly through a fuse from the battery lead on the starter. This way I could run the starter any time while working without the ignition on. When using it for starting I would just reach out and turn on the key and start from below or with the key.
Stay well!
Dave Neptune