It depends on how you create the LODs more than anything else. The digital_instruments.ini file will execute the code contained only if the parent (e.g., display_data) is present, but I believe it is loaded into memory regardless of the distance-based LOD. Unlike LOD_A, the other LODs should have a single null for the cockpit. It's like having a COCKPIT_LR permanently loaded, therefore without the dashboard parent. So, if you create the LODs manually, you can safely delete the parent
So you will have a situation like this:
LOD_A --> COCKPIT_HR (with digital_display parent) and COCKPIT_LR (without digital_display parent)
LOD_... --> COCKPIT (without digital_display parent)