A lot of people are moving out of California because of the pandemic, lack of economic support, and high taxes/cost of living. 

I think part of it is these cases are complicated.. so hard and time consuming to prosecute.the one I have first hand knowledge of here in Oregon.. its the IRS that ended up taking it on.. these guys take this money but don't pay tax on it.. that's tax evasion money laundry and wire fraud..

i love to GC my own flips. i support it 100%

You could use a heloc to source and support down payment for the new purchase.  

If the pet is considered an ESA- emotional support animal you cannot charge a deposit or pet fee.

That is the law that regulates the type of activity you are describing.Telephone Consumer Protection Act 47 U.S.C. § 227SEC. 227. [47 U.S.C. 227] RESTRICTIONS ON THE USE OF TELEPHONE EQUIPMENThttps://www.fcc.gov/sites/default/files/tcpa-rules.pdf 

The seller would like have to carry back 5% - 10% and it would be unlikely to work for the property that is 68% occupied because the DSCR would probably not support an 85% LTV loan, unless you are getting an absolutely screaming deal.Do the 140 units need rehab?

I have found a lot of articles on smart water meters being installed by some city water companies but not much on wifi enabled water meters for consumer purchase. 

I run into this situation a lot where owners buy a property and then they move out for some reason and want to rent out the property but unfortunately the property was not purchased as an investment and the income will not support the expenses every month.If I were you, I would look into a different strategy so you are able to have some positive cash flow every month.Have you thought about furnishing the unit and doing Air BNB, or furnished mid-term rentals?

Perhaps.Just to add to what @Tom Gimer: points out, "When the buyer defaults": let's add that the seller can and sometimes does sue the buyer, and sometimes the seller is contacted by an advocacy group or an attorney and the attorney general is notified and if hanky panky is involved it can mean an investigation of bank fraud, wire fraud, violation of the Consumer Protection Act, violation of Dodd- Frank and some state specific charges.