Irrespectively of how BIG textures you want 1 uv texture is enough. You onlyu need a second uvset IF and ONLY if you plan to put 2 textures on TOP of each other.
Beginners often overestimate the size of textures needed for the images they make. By a factor of 4-16 times. Reason is that because they can not quantify what makes into the quality they assume that pumping something up solves their problem. It is only when they can put things into definite perceptive by nailing everything else that they realize that their textures are over exceedingly big.
Same applies for print work by the way people think they need a 1600 dpi image but for the 1600 dpi printer the actual image size is 160*1.9-2.2 so 200 dpi is enough.
, i dont think that 2k is enaught for all the detail,
Well thing is you dont actually need all that accurate texturs in most cases. For one thing your never going to closeup very close on most caharacters whan you do only very specific locations. And if you are then the was bulk of your textures should be procedural, which off course have indefinite depth.
But in fact a 2k texture is Actually pretty damn accurate, if your character is a 1/3 closeup shot on a full film frame then a 2-4* 2k-4k (one for face, one for hands and one for rest of the thing) textures should be enough. Remeber a movie frame is samller than a 4k texture. So if you spanned a 4k texture to fit the entire screen it Should theoretically be enough. Especially if the character is moving (moving causes blur in blur computation smaller textures are better)
Anyway your misunderstanding things just because you cant export bigger psd files does not mean you cant us a lower resolution export as a basis for a indefinitely big file. It doesn't really matter.
Dont tell me that in the CG hollywood movies (no toons but realistic) they use a 1024 file...
no they probably use 2k-4k files however thing is they do use procedural to fill the gaps.
*see the thing is my machine has 16 gigs of memory and sometimes i blow even that out of water. But ive never actually needed anything bigger than 4k for anything. ive sometimes used 8k and 16 k but then whan ive had later time to exel optimize ive noticed that 4 k would have been enough.