the fatshark preditor V2 is about as "plug & play" as you'll probably find. connect camera to tx, attach voltage regulator to tx, attach antenna to tx, attach power to voltage regulator (to turn it on). attach the tx on the outside (right behind the gopro) and then run the wiring as you see fit. about as simple as it gets if you don't mind the wiring running around outside of the shell. it gets more complicated if you want it inside the shell only because you have to figure out how to run the wriring.
some people mount the camera to the battery hatch (door). i bought a usb connector to gopro for it, so i now see what my gopro sees. there's next to no set up for the goggle - basically you just plug in the power and you are set.