F1-OPT STEM Extension - self-employed applying for H4

[hrisipisi]

My spouse is currently on an OPT, Stem Extension and self-employed. He will be applying for an H4 (I am on H1B). What supporting evidence should be attached for HIS employment?

I know that OPT allows for self-employment as long as the company is properly registered (it is) and we can prove that he's been actively engaged in a business related to his field of study. What would qualify as an evidence that he's been "actively engaged"?

FYI: The company is an LLC so no payroll checks, just owner draws...

Thanks!