Nice one. Lots of ideas for multiple game systems - I've had my eye on Tabletop Simulator.
I have found the following really useful for 'standard' tabletop gaming:
Joe Legan's
Platoon Forward avialable from the TFL store
here .
'Small' unit - hence the name.
Includes, among a host of other things, randomising enemy units using catergories of blinds; squads, support weapons and vehicles. This is rules agnostic, so will fit into a lot of systems. You can use blind markers, or just treat any terrain item as a possible blind location, so just requires a piece a paper listing the enemy units.
Threat Generation, by Martin England published in Miniatuire Wargames #373, May 2014.
I've used it for squad to platoon, works with Company/Battalion but would easily work for higher formations.
I can't recommend this highly enough; the example is a WWII engagement, but its easily tranferable to other periods and again works with any rule set. All this requires is a randomised 'clock' AKA Direction Finder to work out where the enemy appears, which can easily be knocked up on a piece of paper.
A quick Google didn't find a link to back issues from Mr Hyde's magazines when published by Atlantic, but hopefully a more detailed search - or dropping Henry a line - would solve this.