I cheat...

I have 2.6Tb of hdd space in my games computer and I just have a solo instance of wow for when I want to solo (also use it when I just want to boost a second toon with one of my level 80's) and I have another partition on a separate drive where I have my 5 instances of wow for my 5 box team.

The solo instance setup has all the standard bars and buttons while the 5 box instances have a separate UI setup.