We renovated the SFH and converted the garage to a 2-bed ADU.

During the "fix up" process, you would use a different kind of loan that will end up converting to a DSCR loan once you have tenants living in the unit(s).So, I would need to use maybe a construction loan for the renovations and then convert it to a DSCR loan?

The other watchout is if you lose your job you are required to pay the money back quickly, like 30-90 days with most 401K's or the loan gets converted to a withdrawal that comes with tax implications and penalties. 

., there’s a strong chance you could legally convert to a two-family.

Imagine a 4bed/2bath home with a small ADU in back, a converted garage with a private entrance, or a three-level home with a basement that can be converted into a private apartment.You can get privacy and house hack, but it takes a little more effort.

Bonus points if you can convert an office space or finish a basement.

Where the rest of the world converted to cash, he pressed into assets.

After sitting vacant for a while I'm entertaining the option of converting to residential units.

Convert the property you are living in now to your second rental, and buy a new home for yourself. 

Converting a traditional IRA to a Roth triggers taxes on the converted amount, so plan accordingly.