Fair enough. We're only concerned for your safety and that of anyone who eats food cooked on your smoker.
Perhaps as a survey of sorts, ask some of the competition/professional pitmasters here about painting any internal part on a smoker and see what they say.
UDS'-55&16, Akorn, Bar-B-Q Kettle, Drum Grill, miniWSM, cobweb-covered gasser. I'm JD.