Hi Tom, thanks for the reply. Of course I would disassemble the engine first
can you imagine randomly drilling into an engine? I would plan to tap the crankcase in the appropriate location and of course plug it while running and then unplug for draining and filling with after run oils etc. it's not a new idea clearly as more than a few other 4 strokes have these (OS Sirius comes to mind). Surprised this engine doesn't have it.
The reason I'm interested versus removing tappets (not difficult you're right, but there should be a better way) is also for convenience with the cowl left on after flying sessions. Just extend a crankcase drain/access with a plugged tube to the bottom of the plane and flush and fill with oil there. Much better and as long as you use enough after run to sufficiently coat the crankcase and let it breathe you should be good to go.