Would you think a more elegant design would be something like a ‘Truman Show’ wall/edge somewhere beyond Mars?
Yes, apart from the Mars bit. A closed system, not too large or too small, and without inefficiency and redundancy in its design. There's a lot of theory that goes into design and the spaceball universe in my opinion is an example of poor design, not befitting the greatest designer of all time.
When building something physical, such as a house, we always start with a foundation that is built upon, and it makes sense that God created earth with a horizontal foundation and built everything upon that. It does not make sense for God to create a place for us to exist, and put that place on a spinning ball in a vacuum so stupidly enormous and dangerous to make it impossible for us to explore. I don't believe God would design earth as a ball in space while also making it appear earth flat and stationary - he it not trying to trick us.