I am American, but I moved outside the states a couple years ago, but I expect to start spending more time back in the PNW in the the next few years, and a stretch goal is to be able to accommodate friends and family when they visit, which should be increasingly frequent.

Every system you try will have flaws, or you may salivate over a feature that appears in other software.Some familiar names are mentioned frequently: Stessa, Apartments.com, RentRedi, TenantCloud, Innago, RentManager, Avail, Rentec Direct, Doorloop, etc.I recommend conducting thorough research on each app online to understand their offerings, pricing, etc.

I seek zoning variances frequently in Philadelphia, but its a lengthy process and don't personally find it a worthwhile pursuit for legalizing a second unit in a building.

Can you bring your portfolio closer to save on frequent flights to maintain better control/save time?

I don't invest in multi-family properties myself but one of the Bigger Pockets frequent contributors on these threads is Brian Burke, who quite literally wrote the book on this, I am buying a copy myself, but please read, i think an ebook available too, I do passive investing only in multi-tenant triple net retail but have spent hundreds of hours doing my own due diligence.

A lifestyle that they can travel frequently and for longer.

We hear about off market stuff fairly frequently.

No pool needed.As a frequent mountains traveler I will not consider a unit with no view and no hot tub.I am not experienced in Charleston, but from what I know these would be extras and probably not essential for renting. 

My assumption is $0 rent those months other than a holiday week like Thanksgiving Christmas and Easter, where the projections are showing thousands per month.As a frequent traveler to the area, I cannot imagine much rent revenue in Jan, Feb, March, April, Nov, Dec. 

I also see this frequently around Tarrant County...like mostly Tarrant and Parker where there is a oil/gas lease in place.