Mounting a tool box

[firstwordisee]

New to the forum, thanks for all the helpful information the regulars post here. I am thinking about mounting a tool box behind my license plate on my '12, 1200GS. I got the idea on the forum and have seen a couple of pictures here however the search engine makes it difficult to find more info. I have the standard BMW luggage so there is not really enough room to mount anything behind the luggage (think about this when buying the BMW luggage!)
I was looking at these boxes http://www.pelicancases.com/1150-p/1150.htm.
Any feedback would be appreciated, it looks pretty easy to do but not sure if there is a better option, if box is a good size, if there are problems others have experienced etc.
Thanks.