You could put in a short vertical stud resting on the floor inside the wall and a horizontal bar running between two of the existing studs. A T shape.
The new vertical stud takes the weight and the horizontal keeps it in place without loading the laths too much.
Place the stud where the centre of gravity of the radiator will be in order to balance the load and thus reduce the turning effect on the horizontal part.
The new vertical stud takes the weight and the horizontal keeps it in place without loading the laths too much.
Place the stud where the centre of gravity of the radiator will be in order to balance the load and thus reduce the turning effect on the horizontal part.