Wouldn't the inauguration be a perfect opportunity for Elon's super-engineers to...

[Retrograde]

5. That was my first thought

Outdoor space heaters are common here (although we don't get subfreezing temps as a rule) so it should be simple to set up something on the Capitol portico or wherever to keep Trump and the people immediately around him nice and warm. The "crowd" on the Mall won't be a comfortable, but what's a few frostbitten toes if you get to see the god-emperor

I've spent years in Western New York and Michigan: people in the latter place would consider Monday's weather balmy. And no one is forcing Trump's supporters to stand out on the Mall and wait for him to finish what's sure to be a [insert adjective here] speech.