10 x 20 tent to shade house questions

[Hank Brent]

My collection has grown too large to summer outside in the small spots that they were in last year. I have a 10' X 20' tent that I would like to make into a shaded area in my backyard. It is the type that you see venders under with the 1.5" poles and white plastic top and sides.
Can I use the top that came with it or should I put up shade cloth? If I use shade cloth, how do I keep rainwater out of my Phals on the 75% side (I read another post about dbbl 50% cloth)? Do I need to put the sides on the tent for any reason? The tent would run east to west with a 5' picket fence behind it.
Anything else I need to know?