OK, here's some sketches I made. I think that one important thing for lasting in high wind is that the canopy NOT be fastened solidly to the bus. The wind must be able to escape. I recently bought an umbrella that is supposed to withstand 60 mph wind, it has vents in the top to let the wind out.
Here's the framework as it will look on the bus.
This shows it without the bus for clarity.
The green part is hinged to be lowered down along the side while traveling. Note that there is a green bar between the trusses, it will be welded in with diagonals for strength. The blue extensions will either slide clear inside or be inserted into the end . The extensions could be eliminated if you have a dog nose or mount the canopy in back of the front wheels on a flat nose. I wanted the canopy right behind the door. It could even be made to cover the door in desired, but there are mirrors in the way on mine. The yellow bar just slides over the end of the blue extensions. The red struts can be sliders that can be adjustable for length and also detach from the side and be used as poles straight down. The removable braces and struts can be carried on brackets mounted on the side or stored in a compartment if available.
This is some detail fo the bracket and top of the trusses. I think for most strength the red bracket should mount on a rib, by removing the rivets and then re riveting. I didn't show the bar across here. There are a couple of scenarios here. One would be to have the tarp attached to the bar and with a simple crank just roll the tarp up and leave it there. I think what I'll do and much simpler is have that bar permanent, with angle braces and have some movable hooks, use the grommets in the tarp. At the outer end I think the tarp would wrap around and under the yellow bar, using either tarp straps or ratchet straps to make things nice and tight. Ball bungees may or may not be needed at the sides. I really don't see it to much of a problem to simply take the tarp off and fold it up for transport.
I'm not an engineer, and have no idea about loads and stresses. I have in mind using 1 inch square tubing for everything but the blue extensions which are 3/4 inch.
Hope this gives some ideas.