Shorter smokebox optionon 2-8-0

[Kernow]

All, please be gentle with me as this is my first post on this forum.

Anyway I have modified my 2-8-0 to the shorter smokebox but not sure what to do about the large gap left in the frame below where the extension was.

I could leave it as it is but but it looks "unfinished".

Has anyone done anything about it ? If so what ?

Thanks