How can I edit Basic cfg safely
 

Can someone help please. I regularly edit the basic.cfg file to give me acoustic torpedoes and other goodies before they were available in reality.
I do this by changing the number of the torpedo ie: change 1 to 9 to change a T1 for an acoustic, on the sub I am using and for that year.

To get radar, decoys, weapons etc, I change the date that they were available to say 1940 and then they are available in the loadout menu to use.

The problem is I keep getting CTD's either not long after starting a mission or when I load a saved mission that has been tweaked. This happens with both GWX 3 and NYGM

Has somebody written a tutorial on how to do this safely? or perhaps there is a thread explaining this?