If you are using ethanol fuel, you are better off fuel empty and fogged for the summer. If you have non-ethanol fuel, you can treat and fog, or just start the sled once a month and get it up to operating temp. That's what I do.
Make sure to grease all the fittings, get the track off the ground, and remove the belt for the summer.
Fogging is useless. All it does is gum a carburetor..badly. Yes you are going to clean the carburetors regardless before the season but less crap you have to remove the better. What I do and I use ethanol fuel after the 1st tank of 93 without it. I take as much out as I can, put in some stabil then run it for 10 minutes so the stabil is in the system then hit the shut off valve and let it slowly die out. Also once the engine is cooled down we spray some penetrating oil or lubricating oil and pull it over several times. Once a month we pull the spark plugs and do that again. That way it keeps the cylinders lubricated and helps stop them from getting stuck or rusted up over the summer. I also don't remove the belt either not in any of the 43 years of riding have we done that. Never had an issue at all. As he said grease all the fittings, check the slides/hyfax for anywhere and if possible yes have the track off the ground. I have ours on snowmobile dolly's so we can move them around the garage. Also now is the time to make a list of what you need to work on later on in the summer early fall. As best to do it then and not when its 10 degrees outside with snow on the ground,lol.
We all have our ways LOL
Om my Efi sleds I leave fuel alone (if not much left or pump out) and add SeaFoam
Running dry on a carb sled is ok, but I have seen a residue left behind!
For the most part my sleds are just low on fuel and in an enclosed trailer!