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All finished, YES, 12,000 btu is WAY enough.
https://marinepartssource.com/12-000-btu-fcf-air-conditioner-115v-webasto-fcf0012000gs?gclid=CjwKCAjw2K6lBhBXEiwA5RjtCfpAgcJjJezJo0tASXgHOXDqLyQc0ioVBvjNNWCneGB85_6bntKzARoC5UUQAvD_BwE