not sure how heroic works but try adding PROTON_ENABLE_NVAPI=1 as a launch/environment variable

Have you tried running the game without the patch?

What version of wine/proton are you using? I believe newer versions of proton do what that 4GB do by default. I think it can also be forced in proton using PROTON_FORCE_LARGE_ADDRESS_AWARE=1 but it should be on by default.