I'm assuming it comps out otherwise you wouldn't consider it, but buyers have greater thresholds for quality than renters.

I’m expecting 2.5 to 3k rent. should I assume that I will get stable and easier tenants?

Assuming you do that here you are financing that pre-paid interest over the 30 year period.

Market Conditions Aren’t Always in Your FavorHouse hackers often assume their property will appreciate and rents will rise, but that’s not always guaranteed.

Assuming you go the HELOC route, another option to reduce your costs assuming you have decent credit is to look at credit card balance transfer promotions.Back in 2003-2004 I had HELOCs on my investment properties and interest rates were increasing.

I assume any painter / handyman doing your turnover could do that kind of touch up in almost no time for almost no money.  

I assume many people here do their own cleaning when they got started so maybe it’s well known by people who aren’t me?

@Lindsey Konchar    I assume you plan on moving back into this house when you move back from Costa Rica?

Lenders assume more risk with a higher loan-to-value, so to compensate they'll charge more in points, loan level price adjustments, etc. 

I'm assuming by adding 2 en suites your referencing adding two full bathrooms, rather than one larger master bathroom?