I would think that the stuff would fade fairly easy. Problem is that you still need something to nail the siding to. Therefore you are just adding the expense of siding on top of your plywood while not really keeping the moisture off your wood with an open top design.

Now if you put a small roof over half the blind to protect the back and sides you might get a few more years service out of your plywood. You still have the threat of rain blowing in from the front of the blind getting the wood wet.

I guess it's worth a try.