PV is in inside heated storage. Usually, some stabill in the tank before I putt putt to the marina, drain the water, pull the plugs, shoot some dino in, rotate a few times, plugs back in, loosen the rockers, that's about it. I change the fluids over the winter.
Commissioning: plugs out, cold lash the valves, crank the engines with the ignition switches off to get the oil out. Pull the distributors and prime the engines until I get 40 psi on the dash (some day I'll install a pre-lube system). Put it all back together, get some water to the raw pumps, start it, time it, warm them up, adjust the valves, and blast off.
The others I winterize myself.