Some years ago I installed the older Sky Writer smoke systemon an OS .70fs. I can't remember the plane it was in though, I think A small Decathlon. I may even have the instructions I used to set it up??
Anyway, it really isn't worth it on A small four stroke engine. Even putting the oil nipple in the header and having A pre heater coil around the muffler and header didn't produce enough heavy smoke to be worth the added weight of the oil tank,battery and pump. If not done correctly it can cause some dead stick flame outs too, something 3-D guys sort of hate.
I would just wait until I went to gas, it's A lot of work for the thrill.