The trick was to actually not using a real cube map 
They are just 6 images and I add them to each side, the images are in the texture UI group so the quality is just amazing. Another reason (apart from the cubemap size limit and resource trashing) of not using a real cube map is the transition effect, with a real cube map you would see the textures the same way at each location within the cube and the transition had to be done with a PostProcess effect, so having just a 6-faced cube the transition effect is just a matter of scaling the origin and destination cubes (one must contain the other), fading between them and moving you physical location from one to the other.
You should try to play around with the texture quality (texture groups, and all texture related settings) to achieve what fits best for you.