Can I get around stepped side wall / "joining up" issues by building two separate rear extensions with a small gap between then?

[Alex Jenkins]

Like many houses, my semi-detached house has a slightly stepped rear wall; the only unusual thing is that the step is in the opposite direction from normal, but I don't think that makes any difference from a planning point of view.

I would ideally like to build a full-width single-storey rear extension, but I am stymied by the fact that the slightly stepped rear wall means that the extension would need to meet the rules for a side extension (i.e. be no more than half the width of the house). 

Leaving aside questions of aesthetics and additional expense for the moment, would it be permissible to build a separate rear extension from each part of the rear wall, with a small gap between them? I would potentially then also make the extension from the furthest back part of the rear wall two-storeys.

It's probably easiest to understand this using my sketch, which I have provided here: https://drive.google.com/file/d/1l1601DnFdsjm3RjgrGscq_n5nReb5ZFX/view?usp=sharing