All are incomplete, anus is something that wasn't invented, yet.
You needn't to have full geometric mesh details, unless you are a medicine fan. A good texture mapping would solve the problem. You cannot use a global mapping where the area in question from a texture of 4000 pixels only involve few pixels. You need to have this region to have his own texture.
I have tried to remap with little success, even I can have the region mapped with good resolution, the surrounding are is very poorly mapped with great texture distortion, so the result is a part that can look good surrounded by a part that is bad, creating a great unnatural contrast.
Maybe one day I'll have success......

Stupidity also evolves!