I'll get a picture posted tomorrow that shows the underside of the tail where the bracket mounts and how it covers the hole. Hope it will help.
I'm not sure about the validity of the argument either that mounting the frame slider directly to the engine is bad. You're probably right, if the crash is big enough to damage the engine at the mounting point, you'll have such major damage it's likely to be a total anyway. But I thought it wouldn't hurt to take this into consideration when I mount the R&G's.
Overall I believe in frame sliders; especially for the slow speed low sider or just falling over while stopped.