IMHO:
1) Whether the 2012 oil:water cooler is sufficient for light track duty (HPDE, Auto-X, etc) has yet to be accurately reported here
AFAIK. It might be interesting to go out at least once with just that and see how it goes, it's possible that it's enough.
2) Even if it's insufficient, the big upside of having any oil:water interface is that your warmup times should go down a lot and temps should stabilize more in general (versus just a large air cooler), so I'd be hesitant to just toss it.
3) You *could* double-stack the sandwiches and fit a regular-sized oil-filter, but it may not be as mechanically reliable as a single adapter. Unfortunately, I don't think there will be any reasonable way to re-use the stock oil:water and add an air cooler without double-stacking.
Probably the ideal solution (if there were a readily available kit that were easy to install) would be a single non-thermo adapter plate running short lines to a larger oil:water interface like we've seen in pics of the AM Performance cars, which they're running in Grand-Am races without additional oil cooling
AFAIK, so more than enough for the rest of us (pictured below, looks like it's welded to the beam in front of the engine and right behind and inline with the lower radiator hose):
