I've used 3/8" facings. Sometimes, it's difficult to source 3/8" thick 50A durometer neoprene. I usually try to find it on Amazon. You will need a 2" wide by 3' strip, for one table. 60A durometer will work, but it will slightly deaden the pocket. However, it's not extreme, and you may not even notice.
Keep in mind, the facing is being installed at a compound angle. The installed width does not equate to the thickness of the material. When installed, the facing will actually be wider than the material thickness. What that means, is that your pocket will likely be smaller than 4 5/8". However, since you are sanding anyway, you can sand the facings down to your desired pocket opening. Just make sure that you measure several times, to make sure that you aren't going to far with your sanding.
If you need additional information on the setup and fixturing, feel free to ask.