New Year's update: with the Maruha deep top hats, fresh OEM rubber donuts and bump stops in hand, it was time to disassemble the Maruha coilovers.
Mostly to clean up and inspect, but also to measure general dimensions and travel; you never know when you gonna need data! I will post the findings to a new thread as AFAIK not many people use these and might be of use to someone. One key point is that although Maruha advises in replacing the damper units once shot, these are proper rebuildable units; the bottom cap is removable (threaded not crimped) and there's a schrader valve installed on the bottom, although not visible with the units assembled. Just for science, I am going to check with a reputable damper re-builder on what's possible.