<iframe width="425" height="350" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="http://maps.google, etc, etc, etc.

I don't know anything about widgets but if this is the code you are pasting in, just use a placeholder. The size of the place holder does not matter, it is just a guide for you in laying out your page as far as I can tell, whether the the size of the shape you use for a placeholder is a 1\4 of an inch or runs right across the page, it will always give you the same results. Why? Because it's the html that is telling the browser what size the image has to be, the size of the placeholder has nothing to do with it. In the above example, if I want the image larger or smaller, I have to change the width and height size in the html code (it should be underlined and bold).