I had the same result last year.....not warm enough engine to circulate everything.
I pulled my knock sensor and clear water came out. Be sure to pull that. Drain any heater hoses/shower hoses and blow out with compressed air.
I removed the lanyard kill switch and then cranked the engine a few times to blow out any water (don't know if this is the correct way or not, but I felt better
I also pulled my thermostat and just poured in a cup or two of regular anti-freeze coolant as a precaution. Be sure to start up in spring in your driveway so the coolant doesn't get into any lakes.
Pull out your impellar too. Leave hoses off to dry out.
Drive boat around with hoses off to get any excess water sloshed out. Drive up and down hills, left and right turns. Just gives you a little piece of mind.
I think you are pretty close though....