yeah. I may go that way. I think I also have a helmet bag somewhere. I would think covering the whole helmet would be the same as goggle covers.
I also use helmet bag in the boot bag, and leave goggles in position. Without a human head, the google is inside the helmet brim and the helmet is protected by the gear bag and boots on either side. Plus I don't intend to throw the boot bag around. I have a giro helmet and bag it came with is soft touch fleece like.
If you've lost your helmet bag, you should be able to find people selling them on eBay for about $10. You might have to be creative with your search to filter out motorcycle and bicycle helmet bags as they maybe too big or too small.
My perspective on goggles is that they are a consumable wear item. So while I try to protect them, I know they will get used up. Damage more likely from freezing rain/freezing fog or fall/crashes, than from within the bag.
I don't buy super expensive current year ones, but stock up when there are deals on closeout models, I have a couple new pairs in reserve.