Actually, better evidence is provided by Mitt Romney's own father, George Romney.
He was in the running for the presidential nomination vs Goldwater, and both were wealthy men. (Romney ran American Motors, if you remember, and built it into a prosperous company employing many in the assembly plant in Kenosha.)
Romney released 12 years of his own tax returns. He was found to have not taken advantage of a number of loopholes that would have reduced his tax, and his explanation was that he felt it was his responsibility to support his government in that manner. George Romney had reason to be proud of his accomplishments as an executive, and he did not attempt to hide or hoard his rewards.
I would regard hiding and hoarding as miserly.
Gaming the system does not necessarily mean doing something illegal. To the contrary, it implies you take advantage of peculiarities, unintended applications of ordinary regulations, workarounds, and loopholes to your own advantage. Maybe it's the counterpart of "work to rule" actions in a union shop. "Hey, I'm doing exactly what it says I can do" is legal enough, but it's far from civic-minded.
I would be more comfortable with Mitt Romney if he acted as his father did with regard to both openness and appreciation of the privileges and obligations of personal wealth.