build a five foot sliding platform to hold 500-700 bls on end?

[lorec]

Simular to a truck bed slide, I would like to use 80/20 and build it to my custom length and width. 90% of the bed would be sticking out of the truck. The bed length would be about 6 feet long. I want it to handle 500-700 bls. So the bearings would be able to handle 5ftx700bls = 3500 bls/2 which is 1,500 bls each? bearing on each side? Not sure if this is the right math.

here is how it would look

http://www.pickupspecialties.com/Bed...bed_slide.html


Thanks!

[lorec]

Is this to borring of a subject for 80/20? I will be making this, then of course, add on extras.

BTW, what would be really great is to see if a tool box could be put together with this stuff and be just as strong as a snapon box. Nothing against snapon I like there boxes but they are a bit on the pricy side.