Second hand Access Literider install

Hey all, I just bought a second hand, well used Literider, and I'm missing a bunch of hardware to install it on my 2010 Taco. The guy before me fabricated some t-slot nuts w/bolt welded on to them, then used lock washers and nuts to mount the rails on the outside of the factory bed rails.

While this works, this means that I can't use the rails for tie downs! Does anyone know what the length of those spacers and T30 bolts are in the original Agricover install kit?

Also, I have a large gap at the front end of the rails, so when it rains, water ends up in the front end of the bed like there was no cover at all. I'm guessing a trip to Lowes to buy some weatherstripping should fix that, but if I were to install the Agricover rails behind the factory tie down rails, would this gap disappear?

thanks!