I recently climbed Mt. Shasta by casaval ridge and brought along a black diamond Betalight. I found that the Betalight required a significantly larger platform than needed to sleep because of the space necessary to place stakes and the design of the larger area of a mid. I know a bivy tent is an option in a situation like this but I was thinking there must be a lighter option. So, has anyone successfully used a flat tarp on steep snow over a ledge for 2 people? I was thinking of a setup like the one below where the red line is a treking pole placed at either end of the ledge and the windward side is blocked off with the leeward side open as an entrance. 
