Here is a sample map with about the right amount of water (not much in the late)
http://67.66.187.69/dominions3/bagv1.png
What I typically do is mark about 40% of the border mountains as actual mountains, link all the seas and the isle to the continent and then mark every land province that doesn't have at least 4 land borders as "no-start".
Unfortunately the lack of sea provinces means that most late maps will look rather featureless.
If you want to use that one just let me know or I can keep generating some others.