I was halfway to Chartered Accountant before I had to leave Scotland unexpectedly; sadly, it doesn't transfer at all, so here in the USA I'm just a numbers nerd with a liberal arts degree.

I have found that the turnkey is a little more pricewise but I don't have the vacancy or unexpected rehab costs up front. 

Where is the value add component?

(kitchen cabinets, appliances & tools) This was all planned for and there should have been plenty left over to cover unexpected costs.

Also, there may be some common area electrical / heating that you have to account for.Occupancy - Perpetually full is great and using 5% for vacancy gives you a bit of buffer / wiggle room for the unexpected.

What I think I'm going to is attach this addendum I found online that specifies I'll be sub-metering the two units using option (b) formula based allocation:"If a Utility Bill is sent, each Utility Bill shall be based on either (a) an estimated or actual reading of the sub meter for Resident’s Unit, OR (b) the previous month’s actual bills for the Utilities for the Property allocated to Resident pursuant to an allocation formula based, in whole or in part, upon at least one or more of the following components: the number of Units at the Property, the number of occupied Units at the Property, the square footage of the Unit, the number of occupants in the Unit, and the number of bathrooms in the Unit.

And of course, they should have worker's comp on themselves or if your state allows, a waiver.

I have a good job and a steady income but saving alone will take me years to have a decent amount to cover down payment, repair costs and unexpected vacancies.

Regarding what kind of cash-flow or ratios you need to retire and your concerns with future CapX, you should also plan ahead to have a reserve in the bank to handle the unexpected stuff.

Yellowstone is certainly not the least of these.Just because an event is rare does not mean it can't harm you or cause you unexpected expense.