I'm considering purchasing a condo or a small SFH in the Oceanside/Carlsbad area as an investment property and renting it out on a short term rental site like AirBNB. 

Keep it short and sweet: thank you for your application, the unit has been leased to an earlier applicant. 

I would suggest you also research the zoning code so there is an additional upside long term.   

Hard money loans can be an option, but they often come with high-interest rates and short repayment terms.

Now, I help the same type of clients get financing (both construction and long term) for their projects.

My one tip would be, its not about getting wealthy quickly, but more long term.

That way I wouldn't be subject to long term capital gains tax and save a decent chunk of change.Also, my understanding of gifts, in this case money, is that there is a yearly limit to how much you can give someone without having to fill out form 709.

However, when the first buyers failed to come through with cash as specified in their terms, the seller pulled out and offered us the opportunity to purchase the property at the asking price, and we did.

Jerome, I lived in Lake Charles for a little while on a job contract!

Another possibility I looked into is simply leave the current SFH as is since we have long term tenant, but build ADUs on the lot.