I know Tesla has a pretty sweet setup, but they are usually set up in common areas not in each garage. 

I forget the number right now but if you are within I think 5 days from sale date the lender isn't obligated to reinstate, but still may.You may be able to delay the foreclosure by simply asking for more time, you are now the property owner and have some sway.A couple observations:You don't have title insurance as no title company will insure a trustee's deed in CA, so that won't help you.You won the auction based on your commitment to occupy the property (SB1079), so this is not a quick flip.To buy time and delay foreclosure you can file a stripped down bankruptcy.You can't stop payment on the 86k wining bid since you paid cash at the trustee sale.Generally trustee sale buyers don't have a real good feeling for the property condition, unless you do for some reason, so this is a wild card. 

Plus, the tax advantages of STRs can be pretty sweet.

It is stressful though has not all been wine and roses.. some great years some pretty lean years..

I also stayed at an Airbnb once that let you pick a bottle of wine from their wine rack...another awesome perk to consider!

What's the sweet spot?

Based on your calculation, you retire in 10 years at the age of 49 which is much better than the average person.You will likely have a bunch of paid off houses and a healthy 401k balance.Seems like a sweet analysis.I am happy for you.

I have seen the sweet spot for ARV in Jax SFH lately have been in the $125k-$175k range.

Many people buy in larger cities like this because the paper cash flow looks sweet, but the reality of it, across the board right now - good cash flow equals lower neighborhood class, more variable tenancies, and tons of hidden capital expenditures.

A good income wouldn't be as sweet with no access to good debt.