Well first off, you can't always get over the fences with the super jump, sometime's they're higher than others. As for performing the super jump, crouch and then fire the wave concussor, and before you reach the apex of the height it gives you, jump with x. You can also fire and then highjump, but I've found that method to be much less consistent.

If you use the ledge you don't even need to glitch high jump, you can glitch double jump instead and it's much easier. You can just shoot, quickly jump, double jump, shoot, spin, shoot and you should make it over.

There's also uppercutting under the fences, or getting the invisibility and jumping from the pole over the fence