To your original question,
What year is you 340? I have an 04 and i just did mine through bolted, bolts were either 2" or 2 1/4', the ones that came with the mounts, they were just the right length and I used a 1/2" spacer under my mounts to clear the lip on the back of the platform. Get some large washers though, I'm actually going to fabricate a backing plates for mine. I have a slide on davit system so don't like the idea of all that pressure on a small area near the rear of the platform.