Summer: polo shirt, shorts, crocs...
and, like a Cub, a Champ can only just barely kill you.
Sartorially, I don't care. Obviously.
I dress for comfort, natural fibres preferred. Footwear that doesn't slip, decent eyewear, otherwise unimportant.
And yes, I've had an engine failure and forced landing on a hot sunny day (we had one once). Barring the mid-air, wings falling off scenario, I'll accept the risks.