When Internal usability collides with driving stability, it can be quite a challenge, as both are as important as the other.
Although there is no legislation (other than the laws of Physics) which specifically governs balance, there is a duty of care to keep the vehicle and driver safe. After all of the effort and expense which goes into these projects, to have a unit fail to reach its destination through accidental damage means that all the money and effort has been wasted. Below are some pictures of an articulated smart car, which in reality probably would not be possible but as indication of the effects of imbalance is more than adequate.
Here we see an example of a balanced combination which allows the towing vehicle to operate within its design parameters. This is achieved by calculating the position of the trailer wheels so that the load is shared in the correct proportions between the towing vehicle and the Trailer
Here we see that the two cars inside the trailer are weighed to the nose, thus applying excessive weight to the towing vehicle. This is an example of incorrect design balance, resulting in an overload and possible failure of tyres, suspension drive train and chassis. Overloading is a serious offence and the driver is personally responsible for the safety of the vehicle, so when considering balance spare a thought for the person driving it you could kill them, or yourself.
Here we see that the two cars inside the trailer are weighed to the tail of the trailer, thus removing the weight from the towing vehicle, lifting it off the floor. This is an example of incorrect design balance, resulting in a lack of drive to the driving wheels and no steering from the steering wheels as they are both off the ground.