I just got the draw-tite trailer hitch for my LT1 Caprice sedan. Two questions: First, I will be trailering a small boat (about 1700 lbs) for very short distances (less than 10 miles each way) a few times a year - my question is whether I truly need to install the arms that require drilling into the frame? The hitch bar itself installs with 4 bolts that go through the rear bumper/frame holes (where the Buick brace would go). Are those 4 bolts enough? Second, if I have to drill into the frame, the drilling area per the hole pattern on the hitch arms lines up with the weld seam on one side of the frame - that doesnt make me feel too good, is there an issue drilling through the weld seam? Thank you.