How to Protect Carpet from Furniture Dents and Wood Stains?

We're moving into a house with very light colored carpet. While preparing to move our furniture, we noticed two solid wood bookcases had left deep dents in our current carpet. Also, the wood stain bled into the carpet. The carpet cleaners said that it could probably not be removed, thereby requiring new carpet. We're getting the silicone sliders to put under a lot of our furniture, but is there a way to protect a larger area, like under large bookcases or entertainment centers? We already plan on scotch guarding, so not really looking for that tip. I've heard wax paper? Anyone tried this? Any other ideas?