7135 update
After observing that the taps seemed to be accurate in the center of the Graffiti area but progressively more inaccurate towards the edges, I tried a Palm III stamp. Interestingly, it worked perfectly for the part that would fit over the 7135's Graffiti area. However, I had to cut off most of the gray and green sidebars, losing access to the command stroke and other keys on the edges.