RC runway grass

I recently moved to a new home with a pasture. I have mowed an X-shaped runway, and the grass was really spiky, clumpy and unpleasant at first, but it's becoming a lot nicer where I mowed it. The pasture has fescue, timothy, and some native grasses (plus a lot of weeds), so I'm thinking of planting some new seed just on the runway.

Any suggestions regarding what kind of grass I should plant? Maybe some kind of grass that doesn't form big clumps the way fescue does. The soil here has a very high clay content, and the soil is quite wet in spring, quite dry in July and August, and medium in the fall.

Maybe it's a bad idea to plant something that will take over the entire pasture. But then again if I plant a lawn grass that doesn't get very tall maybe the taller pasture grass will out-compete it anyway, so maybe that doesn't even matter.