Sure, but you had the extra 0.5U that you’d left as a gap. Run the airflow through that, but don’t make it just a gap or you end up with hot air flowing back to the cold side.
I’m not trying to reengineer your product, Ive just had enough frustrations with rack mount hardware to make me cranky if it isn’t just the way I want it!
Both. Do both. Make it easier for them to address the issue than ignore you. Depending on which side of the aisle your MP is on, focus your letter on either “those evil <other side> are doing thus terrible thing, I know you’re bold enough to stand up to them.” or “this policy seems to have the following problems, and it’s leaving you open to attack from <other side>. It’d be a shame if you lost your position over it.”