* design spec — choose some things that are already clear and final. put a bit of such content in there and see if boss is
satisfied.

i think this is basic but valid advice.

* meeting taken over — normal. see if u can discuss things without boss.

* design debates — if his design doesn't add too much to your effort, then accept it. Pick your fights.

Some design decisions you don't need to bring up to his attention.

I think this is basic but valid advice.