West 105/206 has a relatively low Tg (glass transition temperature), the point at which the solid resin starts acting like rubber. Doesn't mean you can't use it. Just don't expect the part to be stiff at elevated temperature. Not all parts need to be real stiff.
Alternatives? Resin Services HTR-212/386-99 (available from Spruce) lists a very high Tg, too high really, and the person who responds to email avoids specific questions. I've built some parts with it, but I'm not buying any more.
Air temp at 220F is possible after shutdown on a hot day...but there is no structural load then. I think a plenum lid would cool very quickly as structural load resumed, post takeoff.