Awsome stuff. The thing I would hate about a covers like that is you forget what's underneath. The atual steel rim is rotting away not getting the attention of washind/setailing when the cover steals all the attention. That's a fairly good price for the whole set. I would much rather paint my rims or get alum ones. My tires are 16.5". I am thinking white rims, alum/silver lugs? Is that a nutso combination?
Here's a pic of the '64 when I contracted a towing outfit to haul the truck home from the crusher. The front rim was painted silver which I though really complimented the truck. The flabed wrecker was a late '90 Ford F500 with alum Alcoa rims.
My '79 will be painted orange and white in the long run along with a tribue decal on the doors of the old uhaul wagon wheel logo.
If you go with the covers, just clean your wheels up, spray paint them with a good rust inhibitor paint and then put the covers on. Also, if you are thinking about covers and still concerned with the wheels underneath rusting, you could get some brush on paint like rust bullet or chassis saver and brush it on. You really can't tell it's brushed on either. That would prevent any rusting underneath for a long time.
Those rims I posted a pic of are Eagle Alloy's, and are only about $140 a rim. Really you would only need 4, cause you would never tell you're rear inners were still steelies.