I admit that is a lot of snow. I have only had 1 winter like that here in Idaho mountains.
When I start plowing snow in the winter, I approach it with "worst case scenario", which appears to be "normal mode" for Norway. By that I mean I plow out beyond where I need it cleared, so that more snow has someplace to go to. Another thing is to plan the plow-cuts where to cut the snow.
What is the point of plowing down the little hill to a small flat area? Does that go somewhere?
Your snowplow is quite wide so it has A LOT of work to do. Wax the surfaces with auto wax. I carry a long (2/3 meter) car windshield scrapper/brush on ATV. I knock off excessive snow when turning plow angle. A shorter plow would be easier to work with than the width you are using. If not shorter, then using a plow angle will help.
A possible solution: Plow 1 time on each side with square blade, the return with angle blade to push the snow away from ATV. Adding a top slick plastic curve part would help funnel snow away from the blade.
Plow in the center first with square blade, the return with angles to either side to push snow away from center.
Yes add concrete blocks or something to the rear of ATV. A 2-up version does not have that much weight in the rear, so add some. I have done the "Get Stuck" exactly as you have in loose silty dirt. It does the same thing in loose snow. OEM tires are pretty good if you don't just spin them to dig holes. It just digs holes. Slower on power works better. Chains would help, but "all bets are off" on hard ice.
You may practise raising plow blade slowly as you come to the end of a run. It will make a slight hill and push snow up higher and away for more runs to the same position. It isn't easy to do with the winch, but I'm getting better in my 1st season. I can get the pile of snow up to about 1.5 +/- meter high with this method.
Some clean-up or fine-tune work with a shovel is usually needed even when plowing most of the snow away. The ATV can do most of it, but isn't a fine scalpel. I put in 1 meter fiberglass top-reflector rods (about 8mm diameter) before the snow season to locate edges and curves of driveway and flat area. They actually help you gauge where to plow and how to do it. They are really great in the dark.
Keep track of Plow-Hours. Plowing snow is considered "severe use" and counts as 2 times hours for oil/filter change and so on. If you keep ATV outside or in really cold place, 5w or 10w 40 JASO MA2 oil OK. Change for summer or warmer weather.
I have trouble working winch switch with fat insulated gloves in the dark. Tough to see it, fat fingers, etc. I am trying to add a LED light only on the switch, or I may find a lighted winch switch that will work. Dunno yet.
If I am wrong or off-base, don't understand, etc, just forgive, read on, and forget.
I like to plow snow, it isn't that hard to do. Have fun doing your snow plow tasks.
YMMV