Reminds me of a story a friend related a long time ago about how to manage bosses. That probably applies to bike sheds.
The general idea is to introduce a glaring mistake into any proposal you make. Then the boss (or whoever feels like bikeshedding) can "catch" that mistake upon which you congratulate them on their infinite wisdom, fix the mistake, and the project can move along.
So to avoid the bikeshed color discussion, just do something totally stupid, like not have a roof, or a wall, then the nit-pickers will comment on that, you can quickly "address their concerns" and proceed to have a bike shed of any color you want.