How to customize modern aircraft gunsights?

Hello, I have made a post in another section of the forum where I listed every gunsight I could find in the Asset Viewer to customize my own aircraft and try out different gunsights in different aircraft. This has been going great.

Using the Userskin feature and replacing the sight texture with another one from the game files is easy, but how do I do this for more modern aircraft, eg. Alpha Jet TH? There is no gunsight texture and it seems like everything in the HUD is entirely separate from the aircraft’s model in Asset Viewer, unlike the WW2 and even most of the Cold War aircraft.
The distinction appears to be that anything alternate Cockpit Sight modes (Alpha Jet TH has CCIP modes for air to ground, for example) is made like this.

Are there any methods I’m not aware of?