Error while loading entity prototype "boat" (cargo-wagon): Incorrect rolling stock bounding box and joint distance combination.There needs to be border at least 0.2 between the bounding box edge and joint.
Modifications: Cargo Ships › Squeak Through

Disabling one or the other loads the game, but I'd rather be able to use both.

I'm using both of these mods together just fine, the issue might be something else.

Figured it out, for some reason the error wasn't telling me about it but, going through my mod list, it was the mod Blueprintable Trains that was causing the issue.

I'll link this thread on their mod page as well so they are aware since I'm not sure if it's an issue with Cargo Ships or with Blueprintable Trains.

This is now fixed, it was an issue with the Blueprintable Trains mod, the author fixed it in their mod version 0.16.18.