And of course screws from MB have 3 mm allen heads. Avoid them.Witek_M,
I think your idea is a very good one. I can make a hole in the bulkhead and cover that with a cap later, if needed. Now I have the drill and the Dremil kit with the cutoff wheels. Either way, I can see a path to success. I asked the dealership for the price of the two screws and they quoted me $10.01 each and also told me that they are out of stock !
Your biggest challenge is to be square with screw head and avoid contamination. Smallest debris from drilling will destroy compressor. Hold valve steady with clamp to avoid transmitting vibration to evaporator. Assistant is needed.
Take some pictures for future generations.