I've already reached out to 85 Design but looking for more, preferably a company familiar with La Mesa since the city can be especially tough with permits, etc. 

You would use the $45k to pay for the 10%-20% down (depending on the lender you find) and your carry costs, inspections and permits, as well as the interest only monthly payments.  

If developing, you will need a full team for entitlements and permitting (civil engineer, survey, architect, etc.).  

Is there any special permit and/or fee to be a landlord in St.

I'd never buy a development unless I was confident in the valuation and there was data to back the feasibility of the build. having preliminary approval is very different than permit ready where you can put a shovel in the ground day one.

Anaheim is a great location if you can get a short term rental permit

Property is exempt from STR permitting because the jurisdiction considers it to be a commercial lodging establishment.We've been pursuing an SBA 504 loan for it, which was going well until we discovered that the sellers have operated it only part-time the last 12 years -- intentionally blocking 60% of available room-nights because they just weren't up for running it full time in their retirement. 

The other 75% of the skills required to be a good developer will have to be learned elsewhere (a good mentor is the best way).These include everything from Zoning/Subdivision/Land Issues to Environmental Issues to Permitting Nuances to Design Issues, plus all the differences in financial analysis.

I am considering $300 night rate with 60% occupancy which translates to $65k revenue per year from each A-frameAfter considering expenses $50k for each A-frame or $100k for 2 frames.I have some questions about this strategy:Did you try to get STR permit/construction permits in this area?

Some folks told me that I should try to get everything permitted, but now the city is trying to shut the entire thing down saying only single family is allowed in this city.