Yep you can see why having a 1 square foot 'clump' would be problematic in a shot like this, youd have overhangs of 15cm.
This (attached) is a quick test of my grass + clover (5% clover is still too much!)
This scene has 400,000 instances, at a density of 2500 per sqm. It runs a little slowly, maybe 30mins to render to 50spp?
Would it be possible to add a sort of "vertical evenness" parameter, so that the grass can scale to be longer or shorter in some random clumpy areas?
For clump sizing it would be OK to use the small clumps for the "lawn" preset, and much larger clumps for the "meadow" and "pasture" presets, which are generally for larger scale scenes with few hard edges.
My usual (old) workflow is to add dummy grass on the lawn surface, but inset 5cm from every edge. Then I use a different "edgegrass" component in that 5cm border area (it's a smaller, shorter, droopy clump suited to edges).
By the way, I'm modelling New Zealand grass. It's the best grass in the world, or at least 1st equal with Irish grass.