I have a Yamaha 250 and don' want to load a bunch of hours on it just to idle...Can't be good for the motor to sit at idle for 8 plus hours as well....
Four stroke motors are very well suited for low rpm operation. They are most efficient at idle and happy doing so all day, every day.
I can understand wanting to keep hours off your primary but in reality, salt kills by exposure not run time. As such, there is no such thing as a “low hour” salt water motor.
Your better off running it all day, every day until corrosion gets you.
as well as having the backup for going out in the ocean just in case...
There is an old and true adage….if a motor can’t plane the boat, don’t count on it getting you home (in tidal water).
As such, I have a really hard time justifying the ROI of buying, installing and supporting a second motor for this purpose. An unlimited towing policy from Tow Boat or similar outfit is your best and most cost effective means of getting home.