Colours "exist" as a fact of perception.

Why do you put "exist" in quotation marks? What does that accomplish? If I chopped off your hand, would you say that the pain does not exist, it only "exists"?

If you're looking for colours without perception, you've missed what normative usage of "colour" means.

I'm not looking for colors without perception; I'm looking for the colors of perception somewhere in physical reality; since colors are real, and physical reality is supposed to be the only sort of reality there is.

You've then covered your views in word salad; I would not attempt to write with such an appalling lack of clarity as you've wrapped your views in in this sequence, except for strictly literary purposes; certainly not if my intent were to inform.

It's not so easy to describe conscious states accurately, and a serious alternative to dualism isn't so easy to invent or convey either. I'm improvising a lot. If you make an effort to understand it, it may make more sense.

But let us return to your views. Colors only exist as part of perceptions; fine. Presumably you believe that a perception is a type of physical process, a brain process. Do you believe that some part of these brain processes is colored? If someone is seeing green, is there a flicker of actual greenness somewhere in or around the relevant brain process? I doubt that you think this. But then, at this point, nothing in your model of reality is actually green, neither the world outside the brain, nor the world inside the brain. Yet greenness is manifestly there in reality: perceptions contain actual greenness. Therefore your model is incomplete. Therefore, if you wish to include actual conscious experiences in your model, they'll have to go in alongside but distinct from the physical processes. Therefore, you will have to be a dualist.

I am not advocating dualism, I'm just telling you that if you don't want to deny the phenomenology of color, and you want to retain your physical ontology, you will have to be a dualist.