I would just take into account that a lower down payment will mean a higher monthly payment so be sure to run the numbers conservatively in order to ensure your STR revenue is able to carry your monthly payment with this higher mortgage cost. 

This negative equity position is one of many reasons that adding ADUs in a single family zone is not typically a good RE investment.OP whatever you decide to invest in, make sure you do thorough and conservative underwriting. good luck You’re right in that the level of underwriting I presented wasn’t institutional level - but for your average person just starting out, institutional grade analysis often makes the thought of investing overwhelming.

Do not bank on setting a new neighborhood record on $ / sqft - be conservative in your numbers.

Conservative, aggressive.

From my analysis—even with very conservative numbers—it looks like a cash cow.

Curious to hear any creative approaches that have worked in today's market.ARV and future value are speculative so when I am looking at property I am looking at it for longer term - does it fit within my strategy based on conservative estimates.

Yes, Spain is one of the countries in which banks will lend to non-residents (they generally don't) but Spanish banks are much more conservative than US banks so it's more difficult to qualify, especially if you don't earn W2 income.

I tried using the biggerpockets rental calculator this morning and the cashflow was negative, but I may have been too conservative with the numbers.

This can be less I just use this as a conservative estimate because the math is easy.   

I haven't read this page to see what's offered as conservation incentives, and then compared that against your local market prices for "junk" land.