I don't remember the name of the model. A lot of Beavers in the '04 and '05 years used a Carefree of Colorado topper that was installed so it was level with zero slope when extended. They could be further extended by pulling on a strap so that they would shade the windows.
If that is your model, you add tension by winding the arm on one end. The procedure is risky to fingers, wrists and arms.
No matter what you do, it remains flat and puddles are normal. If you don't like puddles or puddles that turn into blocks of ice, there is an extreme solution!