Spooge happens. Two strokes just do it, especially if you ride around at low rpm. Remember, there is oil in the gas..
Probably the best way to combat spooge is to repack the silencer regularly and clean the inside of the expansion chamber.
Preventative measures would be to run an oil with a lower flashpoint. Usually the high dollar fancy oils have a high flashpoint that are great for high load, high rpm use, but are not necessary, or even desirable for most tail riding. I like Motul 710, but there are plenty of good options, usually at half the cost of the "good" oil.
Another note on spooge. Mix ratio has little to nothing to do with it. I run 28:1 with my current jetting because it seems like the magic combo. I experience very little spooge.