does anyone have experience regarding torsion induced stress to metal parts, in this case the wing and fuselage attach lugs of said strut.
Yes, actually...but what are you trying to say when you state "torsion induced stress?"
Your wording suggests stresses a twisting load, but without any further information, it's very little go go on.
If you mount the camera on the strut with any kind of a clamp and expose it to the slipstream, you're going to need to have an approval, and in order to get the approval you're going to require documentation showing it's safe for flight (aerodynamics and function) as well as mechanically sound and properly engineered.
Sounds like you're more interested in just clamping something out there and making do. Without more information and an idea of what you're putting out there, it's hard to be anything but very general on the subject. Also, you really can't separate the safety and the legality; they're tied closely together as both are required in order for the arrangement to be airworthy.