Since it would be impossible to guess how deep grass might be at some unknown observing field in the future, the mat will probably be the easiest way to go. Drop the mat on the ground, walk around stomping everything flat and then set the scope up. Second problem is friction. The Teflon on Formica feels very smooth in the shop, but once you get out on uneven ground, it becomes obvious that Mel and the listserv know best - ball bearings will be needed under the rocker box. More pictures and information after a trip to the hardware store.
Third problem is in altitude.
The altitude drive works much better than the azimuth drive. What's missing is smoothness of motion during a slew. The scope sets up a rocking up and down motion while slewing that needs to be investigated and corrected. I suspect scope balance and flexing in the altitude drive system to be the root causes. This adds flexing to the system while making parts alignment difficult as well.