I am wondering if I can freeze a wasc filled and crumbcoated with buttercream? Has anyone done this successfully?

Yes, I have done it a couple times. It actually worked out really well, I could hardly tell it had been frozen. The only thing I noticed was that it was a bit moister than usual.

awesome! Thank you!

This is how I have always prepared my 2 layer buttercream filled cakes. Once the cake is cooled I place it on it's covered foamcore board, fill,stack and crumb coat, let dry. I place in the freezer (wrapped). Depending on the humidy (live in Fl) I take the frozen cake out that morning leave it loosely wrapped on the counter (a/c room) and I can decorate that evening. If a little moist just run your spatula over the cake and it will be ready for frosting. I also like to crumb coat my sheet cakes when warm, makes for a very moist cake.