If you are anywhere near the south end of the Twin Cities, I've heard great reviews of a montessori school that caters to HG kids:
cyprus

There is also a good school-within-a-school on the north end of the Twin Cities that sounds great for the self-directed HG learner. It's a school-within-a-school that has kids age 5-17, ability and interst grouped, as opposed to grade levels:
Lighthouse

There is also a highly active GT homeschooling community, plus several other self-contained GT programs around the Twin Cities. I'm not telling you all of this to suggest that you should move here, but rather to point out that your chances of finding a better fit educational opportunity for your kid will increase in a major metro area. Also wanted to point out the various different types of schools that might work for very PG kid.