If you are open to non-traditional methods of financing, you could use a debt service loan to bypass that requirement.

A phone call is far superior.

I want this to be acceptable long term if I keep this method of financing. 

Yes, it's true that you might be able to find a product you need at a greater discount when a brand like Wayfair or CB2 is having a sale, but I've found that they truly do offer superior discounts at scale, even considering the fee. 

We've also advised this method to our investor clients that borrow from us.

Definitely do more research on the BRRRR method as that sounds like what you're trying to do.

House hacking is the best tried-and-true method for new investors in my opinion.

I hope to find a single-family home with at least 4 bedrooms, use the BRRR method to turn it into a short-term rental property.

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.

I think a heloc is a solid method to fund a flip.