I should take a pic of my P-182 system. Most of the cables run under the motherboard. The only mess is probably around the graphics card, what with the headers and all. Makes future changes much easier...
That said, I think I'm going to go for a modular PSU on my next build.
Fortunatley the sides of my case are opaque and, because of my lack of cable tidying finess, will always remain so.
I'd be interested in seeing your case though and details of some of the methods you used.
And i'm deff getting a modular psu next time - they were designed for ppl like me.