[cleszkie]

Is the tent portion going to be supported by any sort of foldable frame? I'd get that squared away before putting any needle to fabric.

I live near the Pacific coast and there are a lot of boat canvas shops around that have the ability to custom make any sort of Sunbrella/Sharkskin enclosures for boats. If you have any these type shops near you, you should look into having them build the canvas. It will cost a little, but you will be able to have windows, zippers, screens, vents, etc. sewn in that will take the function to the next level.