I know they have been using EFI on 2-strokes for a while.
Even the government is spending money on making their UAV's a 2-stroke with EFI.

It is possible to run a o2 sensor on a 2-stroke and it work. You just need to learn how to set it up.

The easiest ways to set it up is to not have a two stroke that has a very high specific power (hp/cubic inch) output.  If we use port timings and an exhaust system like what is used on a leaf blower, weed eater or boat engine, it is not real difficult to them run real well in closed loop using an O2 sensor. 

I know a lot about the government 's two stroke engine UAVs.  I have been doing consulting work on some of their two stroke engine projects for about 3 to 4 years.  One of our two stroke projects recently got cancelled.  Now the government wants military equipment to run on diesel even the UAVs.  There are already some diesel powered UAVs being flown.