Great So Cal appreciation, more politically conservative, and you are still dealing with higher numbers.

haha ... in many Asian cultures generational wealth is the default, not the exception, the elder generation passes them housing, a vacation home, a business, a company, mineral rights, and sometimes a political position as well lol it is a way to continue family (and dynasty) legacy so you (as an elder generation) would be remembered  by the community.

Here are a few initial questions that I have: - I'm wondering if there's a recommended corporate structure for these type of business activities, focused primarily on both short-term and long-term rentals.

I'm still seeing a lot of these assumable mortgages go as cancelled/expired listings, I reach out to the seller directly as this is how I've built my Real Estate Agent business since quitting corporate just over 2 years ago.

Let's leave the politics to own that BS world of the only choice is 1 extreme or the other. 

My guess is political noise is going to spur action with both the CFPB to regulate these transactions and with investors calling the loans due. 

If I had to try and sum it up it would be: Form a corporate entity for asset protection; buy properties using leverage to maximize the use of your money; write off your expenses through your business  including depreciation, taxes, insurance, repairs, etc to maximize your tax deductions.  

if you talk to other investors that flip properties the majority will tell you that they have an S-Corp or LLC with S-Corp election. 

You would benefit to consult with a corporate attorney and CPA in your area before making a decision and to come up with your plan.

If you get a title policy, it will insure your leasehold interest not a fee.Also, I believe there's no HOA, only a BODs of the corporation that handles its administration.