Bob, before you work on the spats, work first on the jumpsuit. If you have the vest, make the spats lighter with the bleach and water solution and make it the same color as the vest (the best you can). Just 2 hours in the water, and then dry it outside.
I used RA's spats, and I used the same bleach process i used for the jumpsuit, and they came out excellent...same color as the vest (yes, it came in the mail dark grey, the same grey as the inside of the vest from RA).
You won't go wrong with this.
Robert