LazyDunmer: Is the CTD random or can you replicate it at exact spots? What is your load order? What is the mod you are specifically talking about? What are the mods dependencies? Does the npc overhaul mod only alter appearances (for example Bijin NPCs) or does it makes edits to the npcs such as giving them weapons for example? Have you tried the mods page for help (assuming its on the nexus)?
Without answers to all this I can only offer three assumptions: 1) Something else is causing the CTD (but as said you have used alt profiles this is somewhat less likely). 2) Either the mod or the resources it uses is missing something vital that the game is trying to load. The game can't load and thus CTD. This could be caused by a missing file or mod conflict. 3) Something in the mod or the resources has got corrupted in which case redownloading and reinstalling should fix providing the uploaded files by the mod author are ok in the first place.
Fyreus: I can replicate it by enabling any resource or npc overhaul that has the npc replacement files in them. Everything ctd at the bethesda logo and there are no missing masters in 3 of the 4 (pandorables is missing masters but i decided to go another route) and the mods tend to use high poly head (which my char uses), ks, apachii, facegen, and even with nothing else loaded it still does this and even does it with all the dependencies and i don't know how to look for corrupt files where as autoclean doesn't see any errors in these mods.
Going to try downloading them again or maybe make a mod list and do a clean install again just in case. So far i don't know any gog users that have a ton of mods so help is limited here
I have KS Hair HPH and Apachi. These are all fine. With bad meshes and textures you will know immediately when you see them in the racemenu. Texture mods as a rule will only cause a problem when you encounter them, if they are bad. They shouldn't affect the loading screen at all. Missing masters can definitely be a problem so try disabling the Pandorable mod and see what happens.
Also double check with your mods that you have enabled all the plugins. By this, what I mean is check your right pane if you are using MO2. Check the plugins tab if you are using Vortex.
Another possibility that your problem maybe if you crashing on the loading screen is related to dll mods instead.
Do you have any of the following mods: SKSE, racemenu, address library or SkyUI by any chance? Or for that matter any mod which requires SKSE?
One final thing you can try is verifying your game files with GOG to ensure your base game is installed correctly.
