In carrying out peer reviews over the past few decades, I have seen folks in the concurrent positions of staffer and board member. Perhaps the situation seemed to make sense, to make good use of a dedicated and energetic person, but at best it is a conflict of interest. It could set up opportunities for creating board policies that benefit staff procedures and benefits, or even direct personal gain -- potentially, self-dealing. There could be many nuances and variations, of course, but none of them are good practice overall. A perusal of the appropriate section of "A Legal Primer on Managing Museum Collections," by Marie Malaro should help to clarify this issue.
Best,
Bruce
Cuartor Emeritus
Newport Restoration Foundation