OK
Ignore the initial post...
I discovered OpenPLi already has the same 2 test screens within it's setup menu, but these do go slightly beyond my screen, so my TV is clearly using a little overscan and I can't turn it off (even via the service menu )
The solution I mentioned above has made life easier with these nice skins, so that'll do for me
(& no, the OSD Position Setup plugin doesn't work on a DM800HD se either lol)
CG