I can get some measurements when I get home from work. What are you wanting to put in there? I might be able to design it so there will be no cutting. Im not sure how easy it will be to make a clean cut into the ABS plastic without it melting.
Possibly a battery monitor. Or if it existed, a smaller multi function display like the one in your first post.
this is one options
Amazon product ASIN B0BC4Q3P26
Or worst case a Victron simple round one, but just not as nice aesthetically for this application.