All the dates on "shut down", "spend ceiling"... are fixed. You just short the market before these dates and close the shorts afterwards. In the end, you should make money. I would but not a lot that I need to back up my truck.
If you have time, back test the strategy and let us know the result.
Except for the parks and Washington DC's attractions, you do not feel any slowdown. Most government workers work half of the time anyway. We need a small and efficient government not empire builders.