I agree with your current interpretation. A 0.1 mm tape would be sufficient to represent the backseat and support is not defined.
The rest of your suggestions are not interpretations, but proposals.
As of these, it would need to be supported first by any of the CGG’s.
I am not recommending calling these interpretations, but proposals.
I am not supporting it anyway, as I pointed out earlier. I think it makes unnecessarily complicated rules and against the EPIC agreement as DN should be simple to build. Specification changes are to make building more simple and easier. Bringing rules that making unnecessary complications does not make it easier to build.