My wife briefly help a friend manage their monthly short term rental in San Francisco while they were traveling and have a few friends that do it.Monthly rentals seem to book pretty well, but not at a significant premium to long term term rentals. 

There are multiple ways to invest in RE: single family, multi-family,  long term rentals, mid-term rentals, short-term rentals, rent by the room, commercial, co-ownership, syndications (I personally won't do syndications) etc. 

I would think transient room mates on renewable short leases would be much safer than bearing the brunt of San Francisco's LTR tenant laws.

When you do a traditional 1031 exchange you have 45 day identification period, to provide a list of potential replacement properties and 180 days to close on a replacement.

Short Sales, Bank Owned, $/sqft, school district, days on market, etc.  

It seems to me though your short term objective is to get the HOA to take immediate action on the roof.

Short Answer is yes, via interest tracing rules. 

I’ve been hearing some chatter about large hotel chains lobbying significant funds to push for regulations or outright bans on short-term rentals like Airbnb.

This plays into the affordability issues for tenants by allowing them to live in nicer neighborhoods for less money, yet I get monthly revenue comparable to short-term rentals.I have also shifted my focus to buying better.

Which reminds me that I should mention that I’m not opposed to living a not-so-luxurious lifestyle in the short run.