I've lived off grid in Trapper Creek Alaska for 22 years now and we just covered ours with some plyboard and went out and tipped the board off them once in a while until we built an insulated generator box. Board worked great. You dont even have to put it on them, you can tip the board so snow don't get on them just slightly slant it over them.

It would help if you dug them out of the snow. Geez 🙄

The cheapest solution: A square of wood, about 4 feet square, 4 feet high. Place the middle generator in the opposite direction of the other two so that each gets some of the warm air from the other. It would be ideal if the exhaust gases were discharged directly from the housing. A horizontal plate with a foot distance above the square can keep most of the snow out of the box and allows air exchange. The remaining snowflakes thaw immediately.

Where are you doing better? In a room at a tolerable temperature? Or naked in a snowstorm? Your generators are no different. You don't have to find a specific technical solution for this. It is enough if the generators are somewhat protected so that no snow can penetrate during operation. The thick hose is the vent of the crankcase. This is intended to return the combustion gases that have cheated their way past the piston rings back into the cylinder together with the oil mist. If the gases become more and more with increasing wear, they can carry oil particles with them. If the hose is not attached to the carburetor, then the generator housing is soiled from the inside. If ice forms somewhere inside the generator, this is a clear sign that the generator is too cold. Cold air alone is dry, but with snow comes a lot of moisture. If ice forms, the control functions can often no longer work reliably. The generator blows out a lot of warm air at the back. If you direct part of it forward, then nothing will freeze anymore. It's just a suggestion.

If it's too noisy run a longer cord or two further away. Covering the entire generator with snow was never gonna work long term..