If you want to add it to places like affordablehousing.com then that gives you more exposure.  

Here is a list of what adding ADUs in my CA market is typically a poor RE investment:1) The value added by the ADU addition is often significantly less than the cost of adding the ADU.

You want to make this clear that additional items need to be purchased by the guests so they are aware.

Additionally, do you have any other ideas or strategies that might help achieve his goals without incurring a tax liability?

In addition to that, platforms like HomeAdvisor or Angi are great for finding vetted professionals, and local builders associations or the Greater Beaumont Chamber of Commerce may have directories or recommendations. 

Both properties have a substantial amount of equity that’s essentially sitting idle.Would it be a good idea to tap into this equity (through a HELOC, cash-out refinance, etc.) to fund future fix-and-flip projects or purchase additional rental properties?

In addition to other tax strategies like a cost segregation study on the fully rented out house.

Additionally, ensure that all necessary notices for filing an eviction have been posted and properly documented in your records.

Budget Wisely:Make sure your budget accounts for the purchase price, the cost of the renovations, and any additional charges involved in flipping a house.

So additionally, that there's only 30 days to close and it eats up time for an inspector to schedule time to come.Do you allow inspections of your contracts?