Thanks for the replies,
Here is the solution I implemented for my copy of the game. The mod assumes a BoA1 world (i.e. BoA2, ACW, or NCP does not exist).
1. I did not use CoastalWaters terrain type because when you mouse over the lakes they are green. (which is fine, I just don't like it for BoA1). Maybe this can be changed somehow?
2. I did not use terrain type NoFreezeShallow, because that too caused various graphics issues, not to mention diplaying the wrong terrain type on the terrain pannel.
3. I did use the Great Lakes area and the associated weather pattern. I set the lakes to freeze 5% and blizzard 5% for the months Dec-Mar and freeze 5% and blizzard 0% for April and November. Snow was set much higher in these months. When it freezes (frozen or blizzard) troops can pass over as they do now.
