by season I mean 6 warm months. If you are in Florida thats another story...
Though you didn't use it much, it still sat after being used and that is just as bad as being used, especially in salt.
You didn't mention bottom paint so I assume trailer?
I think it is probably wise to remove the lower unit every season so you never have a problem when you eventually try... can you say "$napped bolt$"..
The water pump impeller will last a couple seasons but when it goes, its a big problem and you are underway and screwed.
That is a true MAINTENANCE item. You replace it when its still GOOD. This really is a do it yourself job for $35. Doing that job forces you to remove the lower unit.
Gear oil, grease, and fuel water separator....MAINTENANCE.
On 2 strokes, generally spark plugs are a seasonal thing due to carbon and oil buildup. You can clean them...but you have to take them out so why not replace them...
Thermostats...same thing..you have to remove them to inspect and prevent snapped bolts and corroded housings. So they'll at least need a new gasket...so why not change them.
Zincs can last several seasons but they should be brushed clean and inspected.
I am new to my Ox66s this year and I hear that cleaning the O2 sensor is a must.
I see that there are a couple anodes in the cylinder block that should be inspected/replaced, they require gaskets too.
Doing these things at the beginning forces you to look at the engine, run it with the cover off...find the "oh crap, that don't look good"