Is it possible/safe to remove the GTAO DLCPacks/RPF's?
I'd like to reduce the overall file size of the game as much as i can, And since GTAO bloats the install and doesn't really get used when playing modded SP is it safe to remove then via OpenIV, Or do most mods depend on content from them?
@Neoprimal Is it possible? Absolutely. Is is safe? Yes. Do you need to do it from OpenIV? Yes, just remove the dlc lines BUT you need to do it from the game version and your mods version of dlclist.xml.
Your last question is more difficult. Much of the updates are still used in SP.
If you made modifications to a dlcpack, then you will need to keep at least the mod version. Obvious issue will be dlc vehicles disappearing from traffic. Same for any peds. All assets that can be used in SP will be lost, including sounds, handling, etc. Some dlcpacks patch issues as well - so you will have to experiment.
If you are looking at saving disk space you can delete them from the dlcpacks in your games folder and from your mods folder (if you copied them there as well which is usually unnecessary). If you change your mind, do a verify integrity to restore if necessary.
If you are looking at just saving game size, then keep the files and just remove them from both dlclist.xmls. You can stop dlcpacks from loading without editing dlclist.xml, it simply won't load them. Or you can remove the lines from dlclist.xml. Either way will keep them from loading but the first option requires less work (just move, rename, or delete the dlc folders).
So the real question is what do you want to keep. The only way to answer that question is to look at the vehicles and peds and other assets in each dlcpack and decide if you need/want them or not. Keep in mind that you can also create your own addons from game dlcpacks. For example, I reverted back but I can still use the new cars from latest update if I want by creating addons - without having those dlcpacks installed.
As for the feasibility, proof of concept. I already did this just as a test. I posted here.