Traveling to the TT with van + bikes

Hey i’m just looking for some information about taking a transit van with two bikes onto the ferry for the TT next year.

Has anyone ever done this? Is there any restrictions when doing this? Fuel levels in the bikes ect. & when booking do you just book the van or do you need to declare that the bikes are in the van?

Cheers.

Source: Traveling to the TT with van + bikes