small omnis mounted against a hard surface = boundary mounted. Usually they are A-B spaced since they are omnis.. but they can also be closely mounted on opposing sides of a flat or wedge shaped surface.. or baffled with a sound aborbant surface like a Jecklin disk. Jecklin disk- I think that is the way to think about how things like the isolation box above would work in these kind of scenarios. I've set up baffles between and behind omnis to reduce the sound from the opposite side (J-disk like) or from the room behind. It can work well and that's what I base my speculation on about the box.
I boundary moount small omnis by gaff taping them onto the back wall, the balcony face, the inner stage lip, or directly onto the stage surface (as long as they are safe from being stepped on). I have a couple hard rubber boundary mounts for the DPA 4060s that protect the mics from being crushed, but those are only really necessary for the protection they offer. DPA also makes a dedicated boundary mounted version of the 4060 in a permanent, weighted mount. Any small omni can be used the same way. The boundary mounting technique increases the mic's sensitivity and the ratio of direct sound over indirect sound, so it can work suprisingly well on the back wall even in situations where omnis would otherwise seem too far away. The pickup pattern becomes hemispherical instead of omnidirectional, but it's that direct to indirect ratio business that 'works the magic' in reducing the room reverb and increasing the direct clarity.
I also have a single directional AT boundarymount mic in a steel casing that could probably survive a hard stomping, though I don't use it much since it is only a single mic. AT makes a bunch of different boundary mount type mics, both omni and directional- probably reasonably priced. The directional ones are like half a cardioid pattern. Crown is the originator with the PZM. There are other companies make versions too. But if you have a small pair of Church, Countryman, Core, MM, SP or other small omnis, give it a try sometime.