Deffo need to take more of the lip off, that's what I did and they fit fine now, try using a dremmel type tool, or even a grinder using a grinding disc, not a cutting disc, just do it bit by bit, check the fit of the light and when you are happy with the fit, job done..
I agree that grinding is far better that cutting.
The only thing that's bothering me is that the light seems to be at an angle. That won't be the rear aperature that's the problem - it'll be the threaded stud at the end of the light. For reference, about halfway down and a third of the way from the left in this picture.
It'd be helpful to have a wider-angle view of what's going on here, as well as a front-on shot with the light removed...