What I did aside from Ualaa's suggestion with copying the WTF files, is quite quick and easy. I delete all key binds, and settings so it is a totally new UI.

Either save your macros in the WTF file, or a notepad and reapply them later.

Turn on ISBoxer's option to have all keys & mouse movements copied on all windows.

Move all your bars, chat windows, health bars, etc.... To where you want on your main. Having the repeater turned on should allow you to do the exact same with all of your slaves.

Then to set key binds:
- Same classes I'll set up repeater regions and set the binds, macros, and anything class specific.
- Different classes one by one.
- Healer separately.