Instead of a cork roadbed, I put an entire sheet of cork on the platform. Since I have traditional 0 gauge and 027 tubular track for 2/3's of my layout, I really don't care about a raised road bed. I get two benefits from this: First, the train noise is significantly reduced. Two, I can use small nails, brads, and staples to affix lights, signs, billboards, and other accessories without drilling or using glues. This way, I can change things quite easily as the cork will repair itself once the pins are removed. As for tracks, I use small screws that will not penetrate below the cork that are also cushioned against the track with a small amount of flexible caulk. This seems to hold the track down quite nicely without penetrating into the platform to create vibration and noise.
With the cork, I can cut green felt and pin it down where I want grass, cutting around the track about an inch from the outer rails. Some double-faced tape can be laid in that gap to which some fish aquarium stones are placed and then glued with a mixture of white glue, water, and a drop or two of dishwashing liquid. I realize that the stones are larger than scale. But when running traditional toy trains with accessories that are not truly scale to begin with, it really doesn't matter to me that much, especially with tubular track. The illusion is still there.
