If the volume is huge, I think we could see a different shipping company involved if Tesla use a dedicated car carrier which can hold up to 4000 cars roll on roll off, like is being done in Europe. It is less than a week’s production so seems quite plausible for the first shipments.
Tesla did a deal with Glovis.
Glovis is being used to ship in bulk to Europe and China.
The car carriers used currently are
Glovis Captain
Glovis Symphony
Glovis Cosmos
Maybe more. All leave from San Francisco.