Is each of the panels 20x22 or both together? Would you want to cut them apart or keep them together? You have a lot of options and room for creativity here!!!
My suggestion is to get some graph paper and play around with it. Cut 2 pieces of paper to represent your panel/panels. Move them around until you like their placement on the page of graph paper, then using pencil, draw different borders and blocks around them.
If you have colored pencils, you can draw in colors you have in mind to see how they play together! This might be a good place to use some handkerchiefs/fabric in western patterns. I see them a lot in thrift and dollar stores. You just have to be careful of the quality.