Thanks and no they are vanilla clouds propably bethesda HD cloud textures if they did something with the clouds that is. Vanilla clouds, RL 3.4a - Vanilla without any RGB tint, No sun glare texture and some tweaks to the sky settings in enbseries.ini and voilá

Using no RGB tints for all the different weather's, interiors and such makes the game rely only on the type of weather or light cast from light sources such as the sun and all the "light bulbs" that emit light from candles and such

Though I had to make some huge adjustments to get it right after I removed the tint saturation, sky intensity and sun intensity was increased alot!
Do that and I will start checking out the difference between the RL Dawnguard patch and vanilla Dawnguard and implement the changes to the main RL file and upload it asap.
EDIT;
Found what the difference was, some Fog Values, sun glare values and something called Trans Delta? which I have no idea what it does. And of course the use of the imagespace "DefaultImageSpaceDungeon" in every Dawnguard interior.