Your last post makes sense to me now. I can see where I'm potentially going to run into the flexing issue. I'm just hoping that 5 upper crossbars attached to a dual rail setup will be more rigid. I'm thinking if the drybox has hang tabs and is resting on the upper crossbars more so when I'm sitting on it, that it will distribute the weight more evenly along the top tubes directly. If I didn't use hang tabs, I would assume that I would deal with a lot more flex if all the weight was resting on the drop rails and full length scout bars.
I'm looking at about $240-$280 for my custom box after my discount is applied. I'm prior military, so I'm used to dealing with chain of command/middle management/middle man. So if I can get a large custom box (that gets good ratings mind you) at under $300, then so be it. It's like wining and dining a woman before she'll let you wear her hips like a scuba mask... Totally worth it right?
Your drybox looks really good by the way. What did it cost you to get it fabricated, and by whom? I'm not one to close any doors, and like to keep my options open.