Running antifreeze overboard even low-tox is just not right and if you read the MSDS it is a haz-mat spill
STEPS TO BE TAKEN IN CASE MATERIAL IS SPILLED OR RELEASED: This liquid is biodegradable but large spills may contaminate public waters. Prevent flow to sewers/public waters. Restrict clean up water use. Notify water supply environment authorities. Impound/recover large land spills. Soak up small spills with absorbent material. Use suitable disposal containers. High biodegradability can stimulate algae growth. Dispose residue to reduce possible aquatic harm.
WASTE DISPOSAL METHOD: Consult with local sewer, municipal, state and/or federal agencies to determine appropriate current disposal option
And that is from no-tox
Most winter sailing is done in small boats with DRYSUITS and anything orginized will have a crash boat on hand
The big issue is what the winter will do to and uncovered boat ,water gets into all kind of places and freezes and cracks ,cockpit drains get ice dams and fillup ect