Cylindrical based interiors

When I try to create a cylindrical (tube) based interior (e.g. a sewerage pipe you can walk in) both the hollow tool and the subtract tools split the resulting brush into masses of sections which leads to terrible lighting artifacts as each are lit independently.

I have also tried creating a tube and placing a light inside it, but that also doesn't work as only the outside can be lit (obviously).

Admitedly this is all happening when I try to have a nice smooth tube with 20 sides, I have tried it with 8 sides as well with the same issue. Essentially I want to create a smooth tube the player can walk through and that is achieved through lighting, the current method means that each brush (after the above process is applied) casts shadows onto the one it overlaps causing hard edges and shadow "creases".

Is there a way (other than creating an entity in Maya or other 3d app) that alows me to create a nice smooth lit interior tube shape?

thanks in advance

Andrew