Seems to me that drilling holes into the lens defeats the whole point of lens/light guards, so I definitely wouldn't go that route. I'm with Trek on this, especially as it relates to #4:

Quote Originally Posted by VX KAT
4) Use much thinner metal for these tabs...would they be strong enough?
Strong enough for what? To be a real guard, or just to stay on at speed and over bumps? If the latter I would think the attachment points could be really thin since the covers will be fairly light and largely out of the way of wind.