On the third hole I decided not to drill that as I have seen several installations without this with no problems. I will be installing a nice mounting bracket behind to ensure a good secure fixing and also these will be mounted on a hard plastic with a 2mm rubber against the bodywork. This will enable more acurate fitting and ensuring the correct position and the catch will not hit the body work.

Worried that the third hole is very close to the edge of the body work and if there is some hlding force on the catch could start to damage fibreglass.