The answer to your first question is no.
You do need to remove anything that might be in your way, but I can't think of anything.
Cut out the bad part of your frame rail, strip the entire area of the frame rail to bare metal, strip 6 inches of material out from the frame rail to bare metal, coat bare metal in weld-through primer, coat inside and outside of thr bad dog rail in weld-through primer, jack the car up and put it on jack stands, use a floor jack to position the bad dog rail over the stock one and tack weld it in place, double check fitment, and finish weld in 2-4" sections skipping around the perimeter of the rail.
Not as nice as putting the car on a rotisserie and stripping it to bare metal, but it'll work.