I found out by accident what covers the R3 well for storage or whatever ... California King fitted sheet fits an R3 with W/S and saddle bags perfectly from front to rear fender corner to corner while snugly holding firm to the floor boards, tall sissy bar, exhaust and bags. Makes a nice dust cover and as an anti scratch layer before a weather proof cover goes on.
I use it mostly to cover the bike outside when I mow or am making a dusty mess. It's very resistant to blowing off in the wind too.
(it's one of our old cotton while linens and not a flower pattern just in case you were wondering)