I bought a BMW dust cover when I picked up my R12R. It was double what the dowco dust cover sells for but....it was SOOOOOOO worth it. This thing is so soft you could use it as a comfy liner for your sleeping bag
.I've been covering it every night after the bike cools down and am very happy with it. The inside and outside of it are both extremely soft so no worries while putting it on.
The cover for the R12R covers the entire bike including the side bags. There seems to be enough give to be able to handle a top box as well. It might start to be snug with a tall windshield AND a top box. Would have to check with the dealer on that one.
Yes it is a bit pricey but this is one happy example of getting a superior quality product for the money.