I’ve got the mobile workstation, and am looking into how I can make a brace in plywood, as light as possible for the extension table. It’s good for many tasks, but not steady enough for work where you put your weight into it [smile]. Especially the plastic lock that connects it to another table is way to narrow. A good start is to look into a couple of brackets to heavily assist the plastic bracket. And always use the adjusters on the feet on both the extension table and main “cart” to support it maximum to the floor.
As Alex and Michael Kellough says, connecting the MFT/3 to something heavy or firm as a wall makes all the difference. The original braces helps, but not too much. I’ve got the VL table at the end, plus another smaller extension table, and now I can do light planing, but not much more.