I have mine down about 1.5" using some 1.5" sq tubing. I also needed to clear the gas line. Never paid much attention to whether it's bowed or not. But it's been undr this 5th wheel for 4 seasons and was on our previous TT for 2 seasons.
1st two seasons it was white like they come. The next 4 it's been painted black to match the 5th wheel better. The paint has stayed on great. Have never needed to touch it up.
I did scuff it up with a red scotch brite pad, apply a coat of Krylon clear and then finish with black Krylon plastic furniture paint.
As gross as it sounds I still like using it. It's right next to my dump valve and makes dumping a breeze. I can fit two Rhino hoses in it along with the screw in sewer connector.
