Covers are not a good idea. More area for salt and debris to collect, pool, and sit. More chance of one of the covers heat warping and contacting a wheel or something. More chance of one coming unglued and causing damage to some part of the car as it ricochets out of the wheel. Do this at your own risk. If you want your calipers to look cool, spend the time it will take to do the job.
Jack it up
thoroughly clean the caliper
newspaper and masking tape to mask the area and caliper
spray a few light coats of paint waiting for it to dry between coats
spray a clear coat and let it all dry overnight.
Remove the nespaper
put wheels back on