For additional context, the property contains two renovated log cabins with various amenities, hiking trails, and a few outbuildings.

This is where most ADU additions have issues. 

I can't afford anything else in Southern California where i live.

For a typical rental of mine, I will use LVP in the living room and maybe dining room (public areas of the house).

Set your own minimum standards, don't let the bank decide that for you, and you may find yourself not living paycheck to paycheck.Oh and don't be surprised when the bank teller makes a funny face when they read your account nickname next time you are at your local bank branch.

Make a lower offer that reflects more than the additional cost of that problem.

I just finished a project in Torrance, CA, and I found that California has a lot of additional requirements related to energy code and seismic design.Construction: it helps to get a contractor involved early in the design process.

A mixed use zone can be a good transition between residential and commercial.Impact - My wife used to live in a dorm with a high speed train going by every couple hours.

If you are expecting this person to go out and source the items and then place them in the unit that involves a lot of work, designer time, and designer energy.One way to get yourself on boarded with a designer would be to make some phone calls and see if they have openings for new clients as far as spending the time needed, because in our business time is money vs a family having their living room dining room and entry hall redecorated, where time is not probably of the essence.

No, if you want a low downpayment you could buy it with a FHA loan and live in one of the units the first year.