Closest aftermarket Haynes Manual to our 2002 E450 V10 is the 1992-2005 E150-350 Book 36094.
Only wiring diagram I could find in all its diagrams that covered Turn Signals was labeled 1992-1996 and it shows the colors KCharles posted above.
Where will the side-view cameras mount?
If they add to your existing mirrors, it could be easier to run the wiring back from the front lights. That's what I did when I added Turn/Marker lights to our mirrors. Note that if you need a ground, the Doors Are Not Grounded! At least reliably. I had to bring a ground wire in from the door jamb.
If the cameras mount to the side of the coach body, probably easier to bring wire forward from the rear lights.
Our coach has a low-mounted midship clearance light on each side of the body, about halfway along the length. Ours is only a marker. If it happened to also flash with turn signals, then it could be the best choice to tap into.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB