Not that hard, you can pop the wires out of the plug unit, noting the function of the cables, brake/side/indcator/fog etc.
Then follow the lines on the back of the light cluster, when you sort out which pins are for which job, pop the spades on the loom in the corresponding plug holes
what you doing about indicators, do you have the bumper unit for them?
What I did I used the bumper units for indicators and fog lamps, leaving the brake lights in the main upper clusters.
If you are in water this means there are no live wires down in the bumper to cause you problems (unless you have indicators or fogs on
)