The Early Mx has almost 50/50 front rear balance,
I guess you do not tow much !! ?
Have a look at your cars towing spec for trailer nose weight. 40 to 70 kg is ballpark for most vehicles. ( make sure your gross train weight is within the cars ability )
Once the car is on the trailer you should be able to move it forwards or backwards to get it right.
A tail heavy trailer is very dangerous and will wag the car, too much nose weight will make the tow cars steering too light.
Try with the back of the door over the rearmost trailer axle and be prepared to move the car forwards a bit more or back.
Check the hitch height between the car and trailer too as this can affect four wheel trailers axle loading and balance.
The car in my avatar goes onto a single axle unbraked trailer for its travels Its only just legal on weight for our 2 litre estate car
( It used to be towed by a Mk1 Escort Mexico )