I don't think you know yet what level of GTness she's at yet. Her scores indicate some LOG, certainly, but at 3.5yo, things are still too uncertain. If she got tired or bored, her scores might not show as well as they could. If she tested at her best and the norming sample didn't, then her scores might drop. You just can't tell yet. She may be an HG+ kid, too.
I completely agree that learning something besides social stuff at school is important for a kid. In fact, I think it ought to be mandatory! Otherwise you're teaching a child bad, lazy habits. That can have some serious ramifications later!

There are other ways to get learning in without grade skipping. Afterschooling is a possibility. Homeschooling for a year instead of early entry might let you see what she's capable of and would still give her plenty of time to play. We could probably come up with other ways, too...