Richard,
That chromed stuff comes in rolls. Measure the space you have and buy the size roll you need for your coach. Cutting the stuff is a little tricky, especially the rear most piece. I would measure each piece for each basement door, then take it to a machine shop that has a 5' (or bigger) metal shear. Have them cut the ends for each length you need, then the rear most pieces will need to be cut lengthwise on a taper from front to rear. Make sure you have enough total length to have at least one extra piece in case it is cut incorrectly.
Good luck,
Karl