I have a low profile over the rails diamondplate box i found at home depot for 59 dollars i drilled holes in the top and put u bolts in it and I have 2 5 gallons fueal cans a 5 gallon water jug and a cooler strapped down. If I need to get in all I got to do is unstrap the water jug and can lift it up to get in it works great .
here is a pic you can kinda see it