we have just got into trolling a couple of years ago but we always use jet divers with 4 foot leaders and then a stinger spoon. we have had great success. i think a harness would work behind a jet to not much difference between a spoon with leader than a harness. as far as trolling with jets we have 4 30 foot jets and we normally run them back anywhere from 80' -150'
alot of times we can get the fish off of the bottom. just watch your electronics and use them to help you pin point fish depths and adjust accordingly. i dont have the trolling book but i think im gunna get it. hope i helped you out good luck.