Snowblower PTO Shaft Source

[RoyJackson]

Great idea, but my concerns with a slip clutch is the snow, ice & water. Are those unfounded?
Seems to me they are designed to work in drier environment. Thoughts?

I wouldn't use a slip clutch for the reasons you wrote...there will be snow and ice between the slip clutch plates. There's no getting around that.
Also, some snow blowers (like my Woods) use two shear bolts. One would be for the auger, the other (a higher grade bolt) for the drive shaft.