Using a drop-in tub as shower?

Hello, My wife and I forsee a potential issue and want to run it by the group. I've uploaded a drawing of the issue to the Photos section in a folder called Shane's -- it's called "tubissue.jpg". We bought a jetted tub that has a lip which is meant to be dropped into a "box" that you frame out. We are going to use the tub as a shower/tub as well. Well, there is a tiled lip that goes all the way around the tub of 2". We are concerned that water from the shower will puddle up in the 2" space between the lip of the tub and the back & side walls. Is this a valid concern? If so, how would you recommend we avoid/solve the issue? We are still in the framed- up stage, so we could eliminate the 2" space, but we'd rather not since it gives the tub some style, for the lack of a better word. THANKS! Shane