Crawling around an engine bay, trying to reach some deeply buried component with three flex fittings on a socket wrench, is nobody's idea of a good time.

Thankfully, at least a handful of production boat builders have recognized this, and offer reasonably good access to the critical bits of the sterndrive system's prime mover.  Still, it seems there will always be a few that insist you hire a double-jointed 8-year-old with the mechanical skills of a Formula One pit crew just to change a spark plug.