Saw a shop called Qatar Tents Factory, its near to where I live, they will probably sell the thicker sail shades you are looking for. Its towards Al Rayyan, go past Villagio, then through traffic lights past Hyatt Plaza to the zoo lights then turn right towards Al Rayyan its just along that road on the left hand side. Its only got a small shop frontage so dont be looking for a 'factory' as the name suggests. If you get some let us know how much they cost perhaps we can all get some.
regards