here is one illustration i did on paint for you....
one thing to remember when you put the four bolts for the setrab use 8 nuts.... the 4 nuts will act like spacers with the setrab cooler on top and then 4 nuts to hold it down
i spaced mine out just so the setrab wont have water stuck underneath it possibly corroding it in the long run i hope that helps you bro....
i imagine you can just get a angle iron made outa aluminum about 1/8 thick at home depot... cut it to fit the size of the cooler and drill out the holes and viola
all done...