I have a Nelson-Rigg travel cover. It's a full cover that will easily fit inside a helmet when wadded up. Seems to be holding up okay, considering the use it has gotten.
My other "heavy duty" cover is one I have used locally and is a Dry-Ryder brand. It did get used as a travel cover for a while but is too big really, when wadded up and takes up a third of the trunk space. Back when I worked, it got daily use but is still in one piece.
I've had both of the covers for probably 20 years or more and the elastic has kind of gone away on both, so bungies are needed. The Dry-Ryder is the more weather resistant of the two and would be my recommendation, if you can find one. It's probably the same thing as the Wal-Mart brand with a different name written on the carrying bag.