Here is my minimalistic UI. It is very small in the consumption of only about 1,000 kb (without skinner and skada).
It is made especially for Pve and solo play. But can you play with PvP, I think.
Delete your Interface and Fonts folder, or make a backup of them.
Copy my Interface and Fonts folders into your WoW directory.
Put the SavedVariables Folder into wtf//Account//YOURACCOUNTNAME
when you would like to use skada and Skinner