So, even "final" PCBs are never finished. Just slept over it a night and added this and that, removed this and that as well.
I ordered them at @oshpark today. Material will be 0.8mm thick, with 2oz copper.
I couldn't find a free to download model of the keystone 3012 battery holder, so I made one myself. This was quicker than registering somewhere and downloading it :)
It's not 100% to spec, but the outer dimensions are correct, that's what I wanted.