No oil expert here, but I'm in the same conundrum. My boat was away having its trailer worked on and I kind of missed my winterization window other than draining the block/manifolds. After giving it some thought, I'm draining and refilling/changing the filter, and fogging. I'm sure it will be fine just this once. I know people who treat their boats much worse.
Previous: 1993 Prostar 205
Red 1998 Closed Bow Ski Boat, PCM GT40, 310 hp, Standard Gear Reduction, Acme 4 blade, Perfect Pass SG/Zbox.
Tyler Ski Club
Be kind. Have fun.