The Siku model is advertised in a 1/55 scale, which is the scale of the towing car. Boat and trailer information listed at the back of the box seems to advocate a 1/52 scale (except for the boat width 1/55 and hectic height scales of respectively 1/75 and 1/96).
The Audi car was replaced by a 1/50 van with real dimensions of both boat and trailer searched and found, to simply add a new 1/50 scale combination:







Renault Trafic 4x2/2 van (modified(*) Solido model) and Harbeck Fahrzeugbau BT 3500 MALM6-Confort 2-axle boat trailer (modified(*) Siku model), loaded with a Performance Marine 807 in-board 2-engine racing boat (Siku model),





Notes (*): the towing eye on the Siku trailer was replaced by a camper-type towing device with a corresponding hook added at rear of the Solido van.

Regards.
Guy

Even when the Siku combination is mainly made of 1/50 models, the recovered car is (badly) reproduced in a 1/55 scale:



With the addition of a Conrad model, you can have, at low cost, a coherent combination in a 1/50 scale:







Mercedes-Benz 307 4x2/2 van (modified(*) Conrad modiel) and Böckmann AT 4019/27 2-axle car transporter trailer fitted with a tilting bed (modified(*) Siku model) carrying a Volkswagen 2T1-1.2 MT 4x2/2 van (Siku model),



Notes (*): the towing eye on the Siku trailer was replaced by a camper-type towing device with a corresponding hook added at rear of the Conrad van.

Regards.
Guy

To be continued.
Guy