Plaids are not really the best choice for a Lone Star. I worked in the Home Dec department of House of Fabrics and don't remember having any silk upholster fabrics. You might want to do some homework seeing if these fabrics are washable. I remember that even the Cotton home dec fabric had washing instructions that always stated to "Dry Clean" the fabric.
I know what you mean by wanting to challenge your quilting skills. I might want to look at wall quilts since the need for washing them are less than a bed quilt. I would Google "Plaid quilts" and look at the pictures to see if you could find something that would inspire and challenge you at the same time. Have fun and good luck !!