Ask Mr. Smarty Plants

Your choices are generally good.  Mr Smarty Plants got lucky while researching your question.  It turns out that the plant record for Carex planostachys (Cedar sedge) actually contains most of the answer to your question.

It states:  "Carex planostachys (Cedar sedge) is named for the plants it most frequently grows among and under: cedars, a.k.a. junipers (Juniperus species).  It is one of many plants evolved to grow in the rich, loose, fast-draining soil created by juniper leaf fall.  For central Texas, herb-layer companion plants for the shade would be Cedar Sage (Salvia roemeriana), Missouri Violet (Viola missouriensis), Violet Ruellia (Ruellia nudiflora), Drummonds Ruellia (Ruellia drummondiana), Baby Blue Eyes (Nemophila phacelioides), and Straggler Daisy (Calyptocarpus vialis)."
 As per weed-whacking, Cedar Sedge can take occasional mowing and light foot traffic as can Violet Ruella.  Missouri Violet and Drummonds Ruellia are both slightly taller [1-3 ft.]; these might not look too well when taken to the ground.  Missouri Violet, Baby Blue Eyes and Straggler Daisy are all short ground covers which will look well soon after they are taken down.  The advice for Calyptocarpus vialis (Straggler daisy) actually recommends these all to be planted together as companion plants. 

  I'd have concern that two of your suggestions won't work as well.   Dichondra argentea (Silver ponyfoot) looks properly low and has an interesting appearance, but prefers sun or partial shade and is considered good for large open areas.  Silver Ponyfoot may not tolerate the shade of your junipers well.  Similarly,  Artemisia ludoviciana (Louisiana artemisia) is also recommended for open sunny areas.  Although it is noted as tolerating mowing, as it grows to 1.5 to 3 ft. high, it may be seriously set back and scraggly from weed-whacking to the ground.

  As you care for your ground-cover, you may want to consider one piece of advice Mr Smarty Plants often gives to people hiding Oak shoots - - If you choose a ground cover that is low to the ground and not too different from the shoots, try mowing high rather than weed-whacking to the ground.  That will trim the shoots off while not particularly affecting the ground cover.  The ground cover will be still pretty fresh and good looking while the shoots are trimmed off.  This is a strategy of hiding the mowed shoots rather than blasting everything with the weed-whacker.