With the obvious downside that it is a more risky approach, especially if you are not familiar with remodeling, design, appraisals, remodel costs, holding costs etc. 

BiggerPockets is full of resources designed to help you along your journey, whether you are just getting started or a seasoned investor.

Here are my options as I see them.1) Build up a separate capex reserve fundI have about 13k in savings and 25k in Roth IRA funds which I can withdraw tax free as a backup, but maybe I should build up a separate capex account since I don't have a designated one.2) Purchase another 2-4 familyI could use my 25k Roth funds as down payment on a 5th property that cash flows around $500/month and look to do a BRRRR.

It is easy to get distracted, but where you focus the most attention will get results. 5) It sounds like you want to live a life by design.

I have working capital, a solid understanding of how to analyze properties and the rehab process, and I am great at design.

I also enjoy designing people's homes mainly friends and family and I love renovation projects! 

We can meet almost any need- plus we can help with design

BiggerPockets is full of resources designed to help you along your journey, whether you are just getting started or a seasoned investor.

The low bids likely don't account for the entire scope of work required to design, permit and build an ADU, including requisite utility upgrades and other site improvements.

In a city like LA especially, you will need to make sure your rental is set apart from others, so I would have a sizable budget for furnishings and design.