Rental rarely re-plumbs, or re-wires a house.There is a class of contractor who is not licensed as a GC, just their own liabiity ins, who will sub to other sub-contractors. 

Property taxes and insurance are extremely low there so my net profits on those two are $1,000/month and $800/month respectively with loans with 6.875% interest rates putting 20% down. 

Don't worry about losing.That is likely not the only reason you are losing.We use this language for our clients, "Buyers agree to limit inspection repair requests to major structural, mechanical, plumbing, environmental, and safety issues."

YUP very easy work around for this but it does take a lender who will be a little less risk adverse than bigger HML that will simply say no title insurance no loan..

Update your insurance.If they do, inform your insurance company about the change in your property's use.

Stop spending.I'd be surprised to see anyone take on a face-to-face mentorship with someone under 18, just because of insurance and legal implications.Listen to your parents, get a degree (something that can't be taken from you), get a job, build some cash.

Prioritize repairs that protect the house’s value, like roof issues, plumbing, or structural concerns

Yes we always account for R&M, capex, vacancy, insurance, property taxes etc in our numbers.It's definitely NOT all properties that are cashflow positive, but we are still finding them.

As for insurers not renewing insurance in certain zip codes it happens all the time. 

If so, what type and amount of coverage do they have carry for them.Secondly, I'd ask an insurance agent I presently use for advice, given your situation.