When you are in those extremely hot temperatures, are you staying in that camp site for weeks at time? If you are, it might be worth making a shade canopy that covers above and around the rig. It would take tall 2x2 poles in front & back, and shorter ones along the sides, roped-& staked all around. Big screws into the ends needed to set through the eyelets of the tarp, and for the ropes to attach to. You might have to make a stand to place on your PC roof to hold up the middle if it sags. You'll want the a/c unit to breathe, allowing the heat to escape out the ends of the gable.
At a family reunion, my cousin setup such a canopy using a huge cheap tarp which provided massive shade for everyone. It was so big that you could surely park a PC under it. I just did a quick search and found THIS ONE
. If it works well but does not hold up well year after year, then buy something more durable. I would first set it up in your back yard at home to learn how it's going to work in a camp site. Of coarse such a canopy would be vulnerable to strong winds so keep that into consideration. It is just a thought, not a proven idea for covering a PC.
Adding reflective insulation on all windows is effective, but that would turn the motor home into a cave. I am just tossing out the canopy idea to avoid blocking out the light and to keep the sun off the entire rig. Unfortunately the blue tarp I linked to will surely provide a lot of blue light inside. A white tarp would be ideal, and cooler too.
There are also window shades available for the windows on the left side of the rig. We have one for our dinette window, shown here in the "stored" position. But the sun still beats down on the over-all motor home.