The management company has replied that they don't coordinate with neighbors and just want me to cover the cost of all the repairs. 

If you think you will have it for less than 4 years I would say go with the HELOC because you have less origination costs.

Since rental losses are typically passive, the best way to offset W-2 income is through Real Estate Professional Status (REPS) (750+ hours) or Short-Term Rentals (STRs) (100+ hours and more time than anyone else managing the property), which allow real estate losses, including depreciation, to offset active income.A cost segregation study accelerates depreciation, generating large upfront deductions.

For those who’ve used it, what strategies or sources have worked best for you when covering the difference between your loan and the total project cost?

Attorneys  dont cost, they pay. 

Rental income is subject to tax, but it is also possible to deduct many costs related to owning and maintaining rental property, including property management fees, repairs, and mortgage interest payments.Additionally, for those investors holding properties in Germany for the long-term, the country's capital gains tax law is attractive.

Refinancing has more nuances than it seems, and so do closing costs.

The very tragic LA fires have generated a lot of discussion about insurance costs.

I personally do not prefer to hold high cost SFRs as LTR investments.  

That may increase your cost or limit the coverage you can get.The Year that the following were updated (either partially or fully) would be good to know:- Heating systems- Roof- Plumbing- electricalSome companies will not write properties with systems that have not been updated.As long as you are living there, the proper policy for a 1-4 family is a "Homeowners" policy.