Especially for people from the US a lot of additional work needs to be done to get things approved. 

I'd love to see if anyone else has any additional tips on this topic!

However, I'm facing a shortfall: I need an additional $300,000 for the down payment due to a delay in cash-out refinancing on three of my properties.

A major expense can wipe out years and years worth of "cashflow'- A property that cash flows on paper is different from a property cashflowing in reality...There are many times additional expenses to be aware of that may come up in some markets that you are not familiar with...in my case some items were pipes freezing over and much higher vacancy than was figured in initial calculations.- Markets that have very high cap rates as a whole such as 8% + are typically markets that are perceived to have much higher risk and likely will have little to no appreciation at best and more likely would depreciate.

There are cheaper one’s in D/F areas but I would be careful as those can create a laundry list of additional issues.

All the social media RE sites.

In addition in virtually all markets the 1% rule no longer works at a reliable profit indicator at high LTV.  

DM me if you would like additional information.

But we aren’t sure if that is the best option to get additional funds.

This is generally recommended, in addition to insurance, regardless of the size of your portfolio to mitigate risk in the event of a lawsuit.