Hi, I like the "Keytastrophe Mainland", I think it can be used as a strong chorus but it needs a middle section.
I took the liberty to write something in 10 minutes, hope you like it
. It is a bit too short, but maybe with some extra 8 measure it would be almost the same size as the initial section.
Since your main melody revolves around D-G, in this little section I go from D to A, creating a new element.
You can also create more interest by varying the main theme/ostinato, because when you compose with restricted harmonies/ranges like this, you can spice things up using some simple variations, especially rhytmic ones.
Keytastrophe Mainland with experimental middle section