These are cheap and have a nylon zip slider so no corrosion issues. My 6ft North midi fits the 6ft bag, just.
ebay.us/m/AE9Nhx
The omen board bag seems well made and works great if you want to use a bag while keeping your setup fully assembled. No zippers at all. With thinner mid lengths it has a little extra space side to side, but not enough to be a problem in use at all.
It's expensive and no idea if it makes sense outside of North America though.
omenfoils.com/collections/accessories/products/board-cover
