You can overcome any obstacle that crosses your path when you have such a strong team behind you.A word of advice: before assembling your ideal squad, carefully assess each member's abilities and shortcomings.

It was a 4 bedroom 2 bathroom detached house built in the early 1900's.

Maybe doing short term or long term rental in CA can get you there a bit quicker but that also comes with many obstacles to overcome.

For example looking for a single family in Newport with a detached garage to convert into an ADU, either that or a duplex/triplex in Costa Mesa, Maybe a SFR in Dana point that has land for an ADU build, etc… We can do our best to get you a 2/1 buydown from the seller to get your initial rate to a more desirable level and then Refi once rates come down.

I'm looking to house hack by converting a detached garage to an ADU. 

You never know when a life event or market event may come up and present an obstacle. 

I then assume I can get at least that for a detached home or detached ADU with separate entrance. 

Then we will also get a permit for the detached 1/1 Ohana.

You have three obstacles in your question:1. 

My protege added a detached ADU via a garage conversion to his property in Escondido.