I can optimize my Carrot website and pay someone to do it for like 500-700 of Upwork.

Would highly recommend @Keith Mintz for this case, he knows San Diego like the back of his hand. 

We like doing that.

Anyone can do it just like anyone can flip a house or run a short-term rental.

Also, they won't be representing the buyer, so no drafting contracts or the like, just vetting and showing.

I definitely agree - not even solving problems like you mentioned - I think its mainly about solving the sellers problem.

So if the short term rental is the first floor might be less likely to cause annoyance vs it being on top or if the beds and living  rooms are side by side or opposite ends of the building. 

Are you looking to do more heavy rehab projects like this one? 

You’d need to check the local laws to see what counts.Tenant Violations: If they’re breaking lease terms—like not paying rent or subletting—you might have grounds to evict.

Focus on attracting midterm renters through platforms like Furnished Finder, especially during slower periods.