oh wow, you are going big! ok, thought you were doing a shorter drawer. well, then yeah...i'd opt for 3/4 then. i'm not sure how heavy mine are. the 6' slides probably weigh 40# for a pair. i made two separate drawers because of the weight and i want to be able to remove them myself, so two separate drawers made sense. i load my with tools all the time and just keep the drawers in all the time. i lose a little cargo space, but with the cap i still have a LOT of space to load stuff on top of the drawer. one thing to note, i've had my drawer system about 4 years and everything i put on the top of the boxes for protection just came off. i used expoy and even glued down VCT thinking it would be durable and last. i finally just sanded the top of the drawers really well and fiberglassed the top. THAT was the best idea i had on the entire build