I also have no problem with adding a important feedback gauge in extra, and have thought about the pillar pods, but what about the steering column pod? Here is one for a vw . . . maybe one could be modified?
http://www.sfxperformance.com/parts/AUM20020.htm

Of course only one or two gauges at most could be put in, if your short you may have trouble seeing the factory gauges . . .