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. 

STR internet guru's seem to be coming out of woodwork the last couple of years.

Instead of throwing your deal out to a bunch of strangers on the internet, I recommend you do your research to find a local expert with 20+ ACTIVE years in real estate in your market.

Also, dont work with big internet lenders like rocket, lending tree, etc.

If you are using a third-party site to conduct the background checks, sometimes they have the option to send a person, a denial letter, and due to the fair credit act it may be required to send them a notice, informing them that you checked their credit and background so that they have a receipt that it was completed.

Check Better business bureau  site for reviews and so many complaints.

Alerts I set up through sites like Realtor.com or Zillow. 

I use DealMachine, and I'm happy with it (I read the instructions you provide at the site, so I actually wasn't surprised by anything).

No, DIY is not the same as a virtual site visit or a study done by engineers @Dana YobstAs @V.G Jason said, you could very likely cost yourself more in time and money.

They will get deported and when they do, I guess young Americans will have to work in our factories, fields and housing job sites and give up the dream of being Youtubers while sponging  off their parents till her 38 years old.