if you get an ez-up...even a cheap used one....yes, they give you shade and are great for hanging things on the bars...right at eye sight!
I have used bungee cords to hang clothes on in lieu of a clothe line, or camping...super cheap, different sizes. We used to do banners for kids sports teams... two pieces of rebar hammered in to the ground, and 3 cheap pvc pipes.... one up from each rebar, two corner connectors and one pvc pipe across the top... you can't hang a bunch of weight on that, but if you are only starting with a handful... 10-15 skirts....that would hold. and breaks down for transport.
And I love that you can sit there and custom size them! That's a great idea! I hope you will check back in after a few markets and let us know what you end up doing and how it's going! Best of luck!