im building a 10 ft long pvc rail. it has a 5 inch sliding surface, it is supprted by 5 evenly spaced columns of two 1.5' tall 2x4s , and under each column is a 4' long 2x4 so that it doesnt tip. does this sound sturdy enough, or should i angle a 2x4 from the tip of each base 2x4, to the sliding surface. ive seen pictures of pvc rails with, and without these angled supports, but idk if the rail will last without them.