As attractive as your offer sounds and your site is indeed a legitimate PR6, there is a downside to your offer. Because your PR6 site is not an adult site but a Marine Boating site, in google's ranking eyes, it's not the same Topic/Niche and thus the site who is listed on your site might get penalized or the PR juice obtained by your banklink would be downgraded by Google.
Not knocking your offer because it's attractive but I thought I would share my knowledge about how google treats backlinks from 2 sites who have nothing in common.
Good luck with your sale though
