Tony,,, that's a good idea I think. They are easy setup and height is somewhat adjustable, should be easy to secure to rails if you have them,, if not it could be anchored to deck. And a lot less expensive than an awning that would attach to the rear. If you do this,, buy a good one, $130-150 range... most of the cheap ones are just that cheeeeep made and flimsy.
Jim M