I have scoured the forum and found excellent advice regarding rail fitment but before I start the dreaded drilling, does anyone happen to know the ideal location / measurement for the single rails for a 3/4 California bed on a SWB panel van. I understand that the Cali bed would need modifying if wanting it to slide all the way back to the tailgate but if I wasnt too bothered about that, what sort of distance do I need to be looking at from the front carpet/rubber mat edge to the start of each rail. Again, I believe that too far forwards could mean not being able to fit the bed in the rails so a happy medium would be great. Any help as always is appreciated.