If you really wanted to prepare you could also carry a smoke hood to keep away the toxic fumes.
Aircraft Fire Extinguishers, Smoke Hoods | Safety and Survival - from Sporty's Pilot Shop
However if you can't ventilate the small cockpit then visibility of the instruments from the smoke is going to be a real problem......
Then you should look at this product which helps you see outside and also see the primary flight instruments in thick smoke.
EVASŪ-Smoke in the Cockpit-VisionSafe Corporation