I am not too clear about your question, still as I understand you need one loosely coupled UI.
you are going through a right approach. still I explain it in sort
DAL (Data Access Layer) > BL ( Business Logic ) > BE ( Business Entity ) > WCF > Proxy Class > UI
if you want to create a high end app then don't use BE in front end because, someday you may need to change in Business Logic there for you need some additional data point's so you need to change BE but new data points have no impact on UI but you still need to redeploy the UI as you reffer BE from UI.
So create separate UI entity you can Name it ALL (Application Logic Layer).
Now How to Use CRUDE using WCF,