RE: Creating smoke with a trainer?
Yes, but don't bother...again.
You could modify the muffler, run a smoke-pump and a seperate tank for smoke oil. It would be an anemic stream of smoke at best. Glow engines in that size range are barely hot enough for smoke oil to burn effectively, but is is and has been done. You just need the smoke-oil to remain in contact with the muffler long enough to burn.
This may be worth a try since it's not too expensive and....it's your plane anyway....keep us posted.[8D]