This is what I mean...you need a Structural Engineer not a mechanical engineer to take a look at the site. It might cost you a few bucks but it's like taking a cab vs. paying for a DUI....If something goes wrong :( Don't chance it. I have done many of these type of installs and I seriously recommend using a structural engineer - hopefully you can use the guy who engineered the structure in the first place. I just wouldn't want anything bad to happen and it's really your responsibility to make sure it's all good.