Culling, cameras and viewports and clipping issues, Oh my!

Ok, Im working on a project, most of the display is GUI.. I have 2 cameras set up, the main camera with a blank background for now, and a 2nd camera that is supposed to be the 'inset' camera.. What Im trying to figure out is how to make it look like Figure 1 all of the time.. and it works in almost every resolution until you go to a 4:3.. when it does whats shown in Figure 2.. How can I clip or hide that somehow?

Im still pretty new to unity and cameras and everything else. If I were just doing this with monogame, I'd use something akin to a scissorRectangle.. but Im not sure how to go about this in unity..

Figure 1 - The right one...

Figure 2 - The evil one.. which is 2048 x 1536.. ipad'ish

Sure I can design an IPad or 4:3 only version of the interface, but for the moment, that's not in the agenda.. it may come to that though..

Camera settings are as follows:

Main camera:

Clear Flags (dont quite understand this) but solid color

Culling mask - set to ignore the city Layer..

viewport- 0,0,1,1

ortho 3.84 size

depth -1

City Camera:

clear - solid color

culling - set to only show city layer

viewport 0.04, 0.325, w 0.615, h 0.6

depth -0.5

NGUI Default 2d camera set to constrain on X & Y

Thought or suggestions on clipping that?