what if you prove that the child won't be living in a safe area, won't have their own room or any privacy, will be living with people he/she barely knows, etc?
Yeah, whether fortunately or unfortunately, I suspect "safe area" and "own room" won't carry weight. Think about it this way -- if all you could afford was a studio apartment in a sketchy neighborhood, you'd still want to spend time with your kid. So I wouldn't spend any time trying to use those issues for leverage -- it won't come across well.
Of the three, the one you could potentially get some traction on is "living with strangers", and you could maybe address that through a "cohabitation clause" which I've heard is focused on prohibiting either parent from having a BF/GF live with them and the child for a set time period -- like 1 year from divorce. If you can pitch that as "applies to both of us, and I'm focusing on what's best for the child", then that could work.
Given that the trial is over, are you more curious about "how it would have impacted results"? Or is there still some decision-making coming up?