I do pretty much like more SD than SA, but as you asked, the money that I have to invest it aint that much, goes between 30-40K to start and will be definitely for long term, as I said, I´m a beginner in this business in the US, as commons says I´m at the baby steps stage right now.

The only time I'd say it's an okay idea is if either: The area you're investing in is expecting so much appreciation that you will easily profit off that (watch out for mortgage interest though...the appreciation needs to be higher than what you pay in that and expenses to make it profitable)You have some specific reason for wanting to do it- family ties, future home, major long-term hold, etc.Maybe I'm forgetting another one, but those two are all I have for now...

I have 2 flips in progress and 6 long term.

Can they prove how long it takes to rent a vacant property?

However with a long hold I do expect San Diego RE to have outstanding ROI.  

Currently, we manage approximately 40 short- and mid-term rentals, in addition to a few long-term properties.

If you qualify for both (you've lived in the property long enough and it is used for investment when you sell it) then you get to take both.

If it's on the higher side you may want to consider it for mid-term or long term rental, but if most stays are below 30 it can be viable for short-term! 

all of them. as long as the numbers work.

So feel free to reach out if there is something I can help you with related to your STR business.Alongside my work in revenue management, I have real estate investments in Canada, focusing primarily on long-term rentals.