UPS will accept packages from any carrier including ones that need a signature, and most locations even  send you an email when you receive a package.

RLI might as well as some other standalone Umbrella carriers.

And my carrier wanted me to get a 4-pt inspection done.

@Esther Rosenberg Proper is a great carrier for STR. 

Just ask the carrier that does your house.

The agent has no clue about what's going on around them and should've found a different carrier where other people [the sellers] are not hurt by the agent's "unsuitability" for the job.You are in a different market.

I believe the best option is to get with a broker who has many carriers and knowledgeable with what you are doing.

Insurance carriers will not provide coverage for this type of exposure unless you have a professional designation or license. 

Here are my key educational points:- Electric Heat --> SUPER expensive for whoever is paying utilities; stay far away from- Knob and Tube --> Not good for getting insurance carriers to insure your property and it is an outdated and expensive electrical system- Always negotiate for lower purchase price --> Just because the numbers 'work' doesn't mean you can't get it for lower.

Find an insurance broker in the area who can shop whichever carrier is the most competetive at the time!