Im a new c140 driver, my folks live on a long north and south oriented private lake. I would love to land out there this winter. My bird does have 800s on her but the skinny scott 2000 on the back, before plowing was necessary how much snow cover would be safe? If i did need to plow, if the ice was typical rough white ice on top that would not be crazy slippery to land on would it? In what ways would it be different than grass?

I want to be able to work into off airport stuff, but dont want to take too big of a leap too quick. What would be your experienced thoughts?

You can land, and take off, in a few inches of powder over ice okay, but even an inch of mash potatos can get super draggy for 800's on the lower power airplanes. A known hard pack is okay as long as you are 100% sure your not going to break through to softer snow. You also need to know that when you come back the snow has not warmed up and made your runway unusable.
Landing on ice is great and much preferred over landing on snow with tires. If you are worried about breaking do this. Go land at your usual airport and instead of using brakes to slow down dont use any. That will tell you your landing distance on glare ice. Forget about cross winds because if you run out of rudder you have no brakes.
The biggest problem with plowing a runway on the lake is the berms. If you get off to the side at all you have no brakes to rescue the situation and rather then grass run off area you have a snow berm that will grab your tire and either suck you in or just wreck your plane.

Here is My old 120 with 8.00 tires and a tired 85. It did just fine in these conditions.

What he said ^^^.

This brings up the old saying that the Inuit people had many words for “snow”. So do we, and Pamr used a couple: “powder snow”, meaning the light fluffy stuff that you can blow around with a breath of breeze....typically the result of snowfall during quite cold conditions. I’ve landed a wheel plane in over a foot of that stuff.

“Mashed potato snow” is the wet, heavy, sloppy stuff......and landing a wheel plane in much depth is not going to end well.

An aquiantence once landed a 172 in about two feet of unconsolidated snow. We loaded up a snow blower in a 185 on skis, flew it out there and used the snow blower Topo make a runway. Worked fine.

Bare ice or just a bit of snow is fine, but remember that the “character” of snow on the ground can and often will change from day to day. Verify on foot prior to landing if at all possible.

MTV

You will also find that once the ambient temperature gets into the minus 20 Celsius range the braking action on ice is actually not to bad, we had ops specs for ice work with DHC6, DC3, HS748, Boeing 727 and Herc's in our COM, both sea-ice and fresh water

Lots of variables to consider. Lots of them have been covered already. I will just add a few notes from my experience.

1. If it is a large, fairly uniform, surface, it will not have the visual cues you use when landing a narrow strip, beach, or runway. In that case it needs to be treated like a night landing or a glassy water landing, with a nice stabilized approach.

2. An inch of snow is no big deal. But an inch of snow with a crust will make for some pretty good rolling resistance. This means you can stop nicely with no brakes, but also that your takeoff roll will be greatly extended. You need to factor this in when deciding if the operating surface is long enough.

3. If snow is new, it won't have a crust. If it is not, I would expect it to be crusted and terrible. It will feel like zombies are grabbing at the landing gear as you touch down if the wheels are breaking through the crust. You need to be dragging any uncertain surface with a clear plan to go-around while you sort it out.

4. The old guard pilots I spoke with when I was getting into frozen lake landings said 1/3 the height of the tire was manageable snow depth. I would say that is too high if you are dealing with crusty snow. I am only on 8.50x6 mains, but I am generally looking for little or no snow. I like to be able to see the color of the ice through the snow. Deeper than that and I usually just figure I will go find a better place to land.

Thanks, sounds very doabe with some care and right conditions.

FWIW I’m a low time pilot(155hrs). I just started landing in the snow last week on 6.00’s. I’ve found that after a couple of test passes, just touching the mains to get a feel for the drag of the snow, that it becomes something you can quickly get used to. Big difference though going from 2 inches of powder to 4-5 inches and that’s all dry snow with minimal crust. Very true about needing a glassy water technique on wide lakes with flat snow, more important on overcast days it seems. With half tanks, two 200 pound guys and fishing gear, I needed 20 degrees of flap to break outta 5 inches of powder in my 150