That said I would start negotiations billing back the full amount of the job to the tenant per their lease agreement and responsibility for the install.

This gives me access to a large network of skilled contractors, including plumbers, HVAC specialists, electricians, and general contractors.I’ve identified a promising opportunity with an auction property, but I’m unsure how to accurately estimate rehab costs with only a small window to do so.

no one - not an agent, a wholesaler, a contractor, an appraiser - is going to take any responsibility whatsoever for anything. 

These are not caused by tenant so would be your responsibility.

Most in BP, from many responses I see do not have to ability to navigate this.

Remain responsible for rent, utilities, and other terms until a replacement tenant takes over.#2 can be a bad option in the middle of winter when renters are harder to find.

I have sent a funds demand via email but have not gotten a response.

If you’re doing section 8 are you finding those numbers to be pretty accurate on that site?

Airdna.com offers accurate data on any given area for short term rentals!

The good wholesalers will have experience, knowledge (provide accurate ARV estimates or at least close), integrity in putting together win-win transactions, and a list of actual real cash buyers ready to buy (or capital/ capital partners to close on the property themselves if they can't find a buyer), so that the seller isn't left in the lurch and harmed by having their property locked up by someone who doesn't actually have any buyers or a clue on how to sell the property, or any money to buy it.