I don't think you can fit a carrier on the back of your Eriba as the bike would be wider than the van. Your options are therefore:-
- on the front end using a bracket like this https://www.domfox.co.uk/accessories-and...r-mounting-kit/ and a Thule Express carrier that grips the ball.
- attach a carrier to the towball of the car [more difficult]
- put the bikes on the roof of the car
If you go for either of the first two ideas then you need to consider the weight on the cars towball. This is typically a maximum of 75kg, but your owners manual should tell you.
This post may be of use:- How to: install the simplest and cheapest front-mounted cycle carrier

Colin

Giancarlo,
the problem with the rear hatch mounted carriers is they can result in the bike wheels projecting back a long way and hitting the caravan when you turn.

Colin

It does get complicated. 24kg of bikes mounted directly on the tow bar bracket would actually add 24kg. If the same 24kg of bikes sat on a carrier on the front of the Eriba the load would be less, probably only about 3/4 of the weight at 18kg as they are closer to the axle of the van. It is down to levers/moments of force. You do have to be careful with the weight though whichever route you take.
They would also be less likely to hit anything if mounted on the van as they sit very close to the front of the van.

Colin