Typically speaking 20% down (80% LTV) is the bare minimum that commercial lending requires.  10% down is unheard of unless you are getting a great deal and negotiate some small seller financing in second position or getting an SBA Loan for acquisition where your business will occupy over 51% of. 

Consider if refinancing after increasing rents could work, and whether MTR/STR demand is strong enough to sustain long-term profitability.Keep as LTR with Minimal Cash Flow: While this avoids a cash outlay, being cash flow negative or barely breaking even isn’t sustainable long-term.

Either1) your startup takes off and you can distribute profit fast enough to pay off your debts, or2) you find another source of $100,000 a year (which barely even starts to pay down the $300k, but might provide a better chance for a better loan), or3) you BK and possibly lose the rental houses to creditors (hopefully not, but we don’t know how they are held), or 4) you sell the houses, take the tax hit, work with the IRS on a payment plan whose interest will be much lower than your CCs, and focus on the startup.  

Most of my fix-n-flips are financially at least second base hits, or home runs, but this one was barely a base hit. 

You know how some states barely raise an eyebrow when you swap out one investment property for another?

I'm barely considering my second house, just bought the first in Jenks school district 10 months ago.

They were just barely decent investments.

Rents in Portugal are very low and barely can cover for the mortgage.

How would they get to any of these subsurface rights with 1/8th acre lots and barely 20 feet in any direction between any houses and any roads. 

At the bare minimum that deposit has paid for the countless hours bidding out the job, and narrowing down a scope, etc...