Grease the trailer bearings and force out any water in the bearing buddies if you have them. Are all the lines in between the live well and the intake and exhaust holes free of water? Water can freeze inside the lines and expand and create havoc. If you can't get all the water out you can pour antifreeze down the live well drain and that may help.
Might also jack the trailer up so that the tires don't sit on the concrete all winter. That can put undo pressure on the tires. Air up the tires to full after it's cold. Air inside the tires will contract with the cold. This is more important if you don't jack up the trailer to take the pressure off the tires.
Might think about changing the oil in the lower unit. This is best done before it gets cold. Water inside the lower unit may expand and break something. Changing the oil will help check and remove any water and make sure that the boat is ready to go next spring.
Check the batter fluid levels to make sure they are up to the right level before you charge the battery. Check each cell in the battery with a hydrometer to make sure each cell is fully charged. Maintenance free batteries are good to go as you don't have to check their fluid levels. I like the Optima Blue Top batteries.
Might take the rods and real out of the boat and put new line on them for next spring. Also get the hook sharpener out and sharpen up the crank bait and jig hooks this winter.
Take stock in your tackle box and see if you need to order any more hooks, sinkers, baits.
Check all the fuses that are used in the boat. Make sure that you have a replace fuse for each one stored in the boat or truck somewhere. This can save a fishing trip if say the fuse in the engine goes out and it's the kind that can't be found anywhere near where your fishing next spring. Getting that OD fuse now and keeping spares in the boat is a smart thing to do.
Check the trailer's light bulbs and see if they can be replaces. Sometimes the trailer lights get corrosion on the terminal and these can be cleaned off with a dremel tool or some sandpaper.
Minnow buckets can be cleaned with bleach solution and put away. A ten percent bleach solution is made by putting one part bleach into 9 parts water. Fill the minnow buckets up with this soln and let it sit for at least 10 minutes. Then rinse out thoroughly and allow the bucket to dry. This will kill any bacteria and fungus in the minnow bucket and help keep the minnow alive the next fishing trip.
Take out the life jackets and air them out. This will prevent them from getting mildew on them.
If you have tools stored in the boat it may be a good idea to spay them with some wd40 to prevent them from rusting over the winter.
Did you clean or change the spark plugs in the engine?
Running some Sea foam though the engine before storing the boat helps remove carbon deposits and works as good or better than Stabile. Sea foam is mostly NAPTHA. Light petroleum distillate. Sea foam will clean out the carburetor and keep the inside of the engine in good shape.
Fogging oil injected into the cylinders will prevent rust and protect the pistons and cylinder heads during the cold winter months. You said you already did that.
I use to run the gas out of the engine. I would pull the gas tank line off the engine while it was running and let the engine run until it stopped. This took most of the gas out of the engine and the fuel lines inside the engine. This helped to prevent the fuel from gumming up inside the motor. But stabil or sea form may make the fuel more stable and then you may not have to run the gas out of the engine. And I was told that even when the gas is run out there still is some gas in the carburetor bowl.
Regards,
Moose1am