Although I am not fitting it to an engine, I am planning to make a bashplate out of plywood.
For a bike, P-clamps to the frame and its secured.
Its light, strong, easily replaced, and absorbs impact well.
I will make a plate for the underside of my sidecar from rectangular sections on a steel flatbar square frame bolted on rubber mounts.
Not pretty but very easy to work with and does the job. Food for thought...
Adventure: it's an experience, not a style!
(so ride what you like, but ride it somewhere new!)