Are you planning to walk in the area? Very few groundcovers will put up with that. But I think I'd recommend one of the quite flat creeping thymes. High Country Garden probably still carries a number of creeping thymes, and they'd be your best bet. It will take some time to fill in, will tolerate quite a bit of walking on (though not constantly--children or dogs playing for example-- and you could mix a few varieties. They release fragrance as you walk on them, flower, attract a lot of pollinating insects, and are pretty much evergreen.

Just to add, zone 7 is QUITE a bit warmer than zone 5. The thymes will suffer some in zone 5 winters but will have no trouble at all in zone 7.

Fragrance could be difficult under your growing conditions. But a couple of groundcovers that will be colorful, spread quickly and work for your situation would be prairie winecups and orange carpet hummingbird.