Niko,
I'm not quite sure what the issue is . . are you breaking or bending the lights or are they just catching on branches or ??? Obviously on your model the directional/tail lights are armoured by the surrounding metal brackets. Are you catching on them going forward or when backing up?
You could temporarily while working put a 2 x 6 across from one side to the other to protect the lights from damage. You could even create some kind of deflector at an angle on that 2 x 6 to cause branches to shed off as well. But aren't you also snagging your rops also ?
You could drop your rops down in back as a very temporary measure too . . . but of course safety is needed too.
It would seem that if you are close enough to hit your lights . . those branches are close enough to hit you or the rops or the tractor. Can you just chainsaw a clear path of branches . . . If this was a path to your wood working area ?