Nauticam SMC scratched

Hi Guys,

Nothing bad about the Nauticam SMC to begin with, the only thing is that I managed to get a minor scratch on the front glass. I contacted my dealer, it can be repaired... by fitting a new front glass into the SMC. Since the SMC is nitrogen filled, it can has to be sent back to Nauticam. I don't know the costs yet, but in order to prevent this next time. I was wondering do you guys utilize the front thread of the SMC to fit for example a relatively cheap UV protector filter?

Does the compartment between the SMC and the filter fill with water? And, does it drain .

Another idea I had was to use a rubber sunprotector, like Hoya is making, the flexible/foldable ones. so that things around the SMC can not get onto the front glass so easily.

Im open for any other options , being more carefull is one, but since I dive mostly in murky waters its more likely to take some precautionary measures.