It will be necessary to carry out a selective “counter-deformation”, because, as already seen, the deformation is greater at clips location than on the rest of the body. On the other hand, I prefer to avoid hot proceeding (hair dryer or very hot water), because it is almost impossible to control the behavior of the plastic material under these conditions, and the remedy may be worse than the evil.
So I make a 10 mm plywood template (the same will fit for both vehicles). I install it at the bottom of the body.
The slots visible in the middle of the template allow the body lugs to take place. The template corners should be rounded.
I apply pressure to the clips location with plastic clamps to avoid degrading the painting.
I let it simmer at least three days per body (one week is better), to get a result not perfect, but enough for the body to hold on its chassis. But, of course, there is no reason to suppose that the deformation will not be back some day…
Into 1 mm thick Evergreen, I cut pieces similar to the original lugs, with just a “claw” longer by about 1 mm. This jutting out, probably exaggerated, may be adjusted after testing. These pieces are glued (Uhu Strong & Safe) on one side of the existing lugs. On the motor car, it is better to glue them towards the front side because their housing in the chassis is slightly offset in this direction. There is also a small outgrowth of the windows, acting as a spring, to cut.
On the trailer driving cab end, Roco has provided the possibility of coupling another trailer, hence the presence of an opening in the skirt to allow the drawbar to pass. But it's really not aesthetic when the DMU is alone. Too bad that Roco did not provide a complementary piece, as it did for its unified railcar trailers.
This is part of my intentions, but I hesitate to start, especially because of the difficulty to reconstitute the paint shades to apply.