Santander ferry - costs with car on trailer

[Mars]

I used to tour with a group of kit car enthusiasts around the UK, Ireland, Scandinavia and Europe. In the past we have taken our 7.5 tonne box wagon with us for support but since Brexit it has become difficult to manage the legalities and insurance of that truck abroad. So, for this year's tour I drove my normal car and towed a trailer. This worked out really well (I attended to a rescue on day-1) and we are aiming to do the same again next year.

Next year's tour will start in Santander, so we will take the ferry from Portsmouth.

As I'm towing a trailer, I would like to explore whether it is possible (or not IMpossible) to put one of the cars onto the trailer for the ferry, and maximise costs this way. We will be paying for the trailer on the ferry anyway, so by putting one of the tourers' cars onto the trailer and the occupants in my car with me, we could potentially save about £1000.

Obviously there's no option for this on the booking site, only to declare the length and height of the trailer which makes no difference whether there is a car on the trailer or not.

Anyone know?

[Magooagain]

I’ve not used that route before but used many French /uk crossings with a car trailer. No difference in price empty or loaded with a car.

[Mars]

Thanks. Makes a lot of sense then.