I know you don't like E2E quilt patterns but this one is screaming for an Autumn Leaves Border pattern repeated in ever smaller box pattern. Start at the inner edge of your border with a corner pattern then horizontal straights, then the corner. Next row have the vertical straight to the first corner, then a corner pattern, then connect with a horizontal straight to another corner, finally a vertical straight to the first row's second corner. Next row vertical straight, then a vertical straight, then a corner connect to another corner with a horizontal straight. Box within a box within a box within a box. As you get to the other end of the quilt, back it out to close all the boxes. Complex but beautiful.