Not much activity on some of there sub-fora, huh?
I recently had a musical theater gig where the cajon was a featured instrument and a mic/stand combo simply wouldn't work.
After some testing, ended up using a Shure wireless lavalier mic; wrapped the transmitter in a piece of foam and gaffer-taped it to the bottom of the inside of the cajon- the sound hole was just big enough for one of my gorilla mitts to fit thru.
using some 'creative taping', the mic element sat atop the foam pack. Tried both cardioid and omni; unsurprisingly, omni had more consistent sound (player used front and both sides of cajon) and was okay with being kicked about/on/off the stage. The cardioid could work with say, a coat hanger armature, IF the player only plays the front...
batteries were a pain- wired versions are available if that would work better for you.
[But] we have to be careful, and willing to be ruthless of our own preconceived notions, if we are to avoid being painted with the same broad brush that we ourselves use to paint. - dwoz