Help with item holding resource pack

I'm trying to make a resource pack that gives a custom texture to a carrot on a stick with a custom model data and makes it so its held differently, i tried making a whole model for the item but this means that in the hotbar it will be much darker which is a problem because you arent easily able to see the symbol on it which is used to differenciate betwee nthe various item in my datapack, here you can see some examples of what i mean:

any help is appreciated