A pure sensor package in the plane won't work, the pattern is to be flown not as the plane sees it (as in IAC) but as seen from the ground.

That said, The SoloShot2 camera controller is capable of tracking my pattern plane very effectively (as long as I keep my up/downlines at a reasonable speed) using a beacon that weighs less than an ounce which I mount on top of my battery directly above the wing tube (i.e. very close to the CG). It's clear from watching a video shot with this that the device is actually tracking the exact geometry that the plane flew. Add the third dimension (which is there because it controls the zoom of the camera to keep the plane the same size in the frame the whole time (within the limits of the zoom)) and you have a pretty good sense of the plane's location in space, track, etc. for the purposes of judging.

It would be a lot of data to interpret though, and you'd have to know when one maneuver ends and another begins to score each maneuver appropriately.

Some day, when I'm rich & retired, I'll play with it, if someone hasn't beaten me to it! :-)

Peter+