Can you describe yourself as being ‘bonafide’?

No. Or rather, probably not in the sense that you mean. "I'm a bona fide person" means "I am actually a person and not a robot or a shapeshifting alien." It does not mean that you are sincere or trustowrthy, just that you are, in fact, a person.

“I’ll try to be bonafide about this” does not work at all; that's not how bona fide is used. You cannot try to be bona fide; a person or object either is or is not a legitimate and literally-true version of the attribute being referenced. So you can be a bona fide Boy Scout, or a bona fide descendant of Queen Victoria, or a bona fide genius, but you can't just go around striving for bona fide-ness generally.

/r/grammar Thread