I'm thinking of buying a couple of these for flooring in my home gym. My gym is in a finished basement with older carpet that will need replaced at some point down the road. If I place these horse stall mats on top of the carpet, will the carpet get stained black from the horse stall mats? Should I place something under the horse mats? Also, any general info on how well these worked out for anyone who uses them would be great. Thanks in advance.