There are 40 jobs on this route. Most will be on the platforms and surrounding station areas. You'll find them quite easily as the stations are small and some only have one platform. I have linked a guide also with screenshots/maps if you prefer that.
If you are missing one camera, it's probably the one at a lake (south of Brading station, past the road bridge and then go down the left path at the foot crossing). This is the only one that is out of the way.
Text guide:
https://forums.dovetailgames.com/threads/tsw2-isle-of-wight-...Screenshot and map guide:
https://steamcommunity.com/sharedfiles/filedetails/?id=22594...