Arcadia wrote:I think, the problem is, that there is no Boundary preset for dress or body

I think the purpose of boundaries is determining the positioning of the clothing on the body, even if the character is scaled.
Unless your jacket is wrongly positioned on the body I don't think that's the problem.
The "problem" is that the bone weights of the underlying body or verts are copied to the clothes. But I think that this is the best that can be done.
Ask yourself: how would you want the clothes to be rigged?
For not-tight fitting clothes you will probably need to create your own complex rig. This is something that cannot be simply done by MakeHuman I think. (you would need to do something like cloth simulation and extract a rig and constraints from it)
Maybe you can fix it by tweaking the rigging of the jacket in Blender.
What is often done is adding additional bones to the loose parts of clothes so they can be posed and animated manually. You could even introduce lots of constraints that make it flow along the body and avoid intersections automatically when the human is posed. (something like this:
http://www.timridgarde.com/showreelDetails.html) You probably understand that such a thing is not trivial and is very hard (or impossible?) to do automatically.
This might be a cool feature for the clothes exporter script if it's useful: define custom bone weights for clothes. But this is difficult to do because there are various alternative rigs. Also the re-rigging would probably not allow adding custom bones to the rig, and only let you work in terms of the bones already in the human rig.