I keep thinking about this issue too, and have thought about trying to make an extendible three piece section of fairly robust pipe. Start with putting a section into cement in the ground front and back of the motorhome. Use about two or three feet, and put it into the cement so it is flush in the ground and the first piece can fit snugly inside the cemented in pipe.
Build up three sections so that the top is about 15 feet or so up. The top pieces should have a pulley that a rope will come through and an anchoring cleat at the bottom.
Once you do that, get a tarp and put it over the rope, and pull the sides down towards anchors in the ground so that it's not touching the sides of the MH. If you think it would help, maybe run the rope through a piece of rubber hose to provide a softer edge to pull the tarp over.
Here's the deal. 90% of the weather is going to leave it just the way you want it, and sometimes you are going to lose the tarp in the wind and weather. But it won't cost much to replace the tarp compared to building a hard sided shelter.
You might have to experiment with anchors, and maybe even guy wires to hold the poles up tight too, but in summer it all just comes down and gets put away. No fuss, no mess.