I had tried with the corner mentioned on the picture, similar to camper crossing and concluded it wasn't possible even with perfect CJ + Air strafing. However, after hearing it was possible, I started looking around and did notice that it was probably possible from the other edge.
In case it was really a question, the jump with scout can be done with a simple CJ without any prior strafing.
It can be done, with 3 jumps, you start from the corner, and go there in third jump.
I never did it myself, but the dude i was playing iCTF did it, normal, unmodified server)
If you are really close to landing it, then just keep trying. If not then I'd suggest practising bridge to rail on campgrounds with the emphasis of consistently landing on the rail platform itself and not using the ledge on the right.