Also, when it comes to availability dates for nations which entered the war late (such as Brazil or the US) you may want to edit them so that the game spawns them correctly. For example, for the KSQ/LSQ, the availability dates could be as follows:
LSQ:
AppearanceDate=19380101
DisappearanceDate=19411207
KSQ:
AppearanceDate=19411208
DisappearanceDate=19451201
This way, if the game spawns a random US Coastal Merchant before the US enters the war, it should be a lighted one. And a Coastal Merchant spawned after December 8th, 1941 will never be lighted. With some ships, Anvart did not release lighted versions,

, so they will never be lit - you can either change the availabilty dates so that the do not spawn until after the nation in question enters the war, or just let them spawn any time anyway.