Activities like tenant management, marketing, bookkeeping, inspections, overseeing contractors, and compliance tasks all count.Avoid outsourcing tasks, as this reduces eligible hours, and consider adding properties if meeting the threshold is challenging.

We discovered problems that required a lot of work and significantly reduced the property’s value, forcing me to lower the price.

Then ask them what your options are to reduce payments in the future.

Freddie has similar intricacies, but also does not require a two year history of receipt; https://guide.freddiemac.com/app/guide/section/5306.4If you can use the rental income to drive the DTI down so that you can reduce the down payment similar to that of the FHA product, the benefits of the conventional option will outweigh the FHA option, as I'm assuming you have a strong FICO based on rate quoted with no points.  

In construction, there is only so much you can do to reduce your margins while staying profitable.

I also would like to reduce the audit risk due to large bonus depreciation. 

Reduced competition and higher prices for renters.RealPage, of course, denies this.

High probability that you’ll uncover an oh-$**** issue that will reduce or eliminate your projected profit. 

Focus on optimizing the current fourplexes (improving rents, reducing expenses).

You could also list the property FSBO at a reduced price since there wouldn't be an agent.