You could probably run that engine all day every day on 24:1 if you wanted to without fouling a plug. Knowing you will not do that I would go with 50:1 for the simple reason that it will better protect your engine through overheats and fuel starvation issues. Both of those issues will create situations where the pistons get hotter than designed parameters and will grow past their normal running tolerances. Once this happens you have very little oil protection from seizing at 100:1 vs 50:1. Main reason is that additional oil helps pull heat away from rotating parts and sets up a heavier boundary layer of lubrication better than the lighter mixture will. Its a win/win situation in my book.
For reference purposes, I run my opposed cylinder engines at a ratio of 16:1 using 50W aircraft ashess dispersant oil with zero plug fouling issues and those engines dont have the benefit of a thermostat. They also had very little spark energy compared to the newer capacitive discharge ignition systems.
Again, for reference purposes only. Carbon forms when oily residue rises in temperature close to or even above that of the designed flash point. KInda like when you started cooking in a frying pan and oil ran over the lip and down near the flame. It turned into a hard carbon residue that you had to scrub off before Mom got a hold of you. In a 2-stroke, using additional oil will, in most cases actually reduce or eliminate much of the normal carbon build up seen in engines since the oil has the tendency to pull heat away from the hottest parts and transfer it to the cylinders and surrounding water jackets. So, what I am saying here is that additional oil will reduce piston operating temperatures and therefore reduce coking. There are other benefits of using additional oil vs going lean on the mix as well.
For those who are interested in engine design and theory of operation beyond what their buddy tells them look up the writings of Gordon Jennings. Gordon was pretty much the Godfather of horspower and longevity in two stroke air cooled engines. He was a brilliant engineer and mainly did motorcyle engines. The air cooled 2-stroke motorcycle engines went through absolute Hell temperature, load, and RPM wise compared to our water cooled outboards. You can learn alot by reading up on him and the neat thing is that most of his testing and findings work very well on outboards.
