One thing to add is that when you buy a new build, your PITI will likely not be factoring in the correct state tax number.

When I'm looking at potential opportunity, price isn't that big of a factor.

When considering refinancing, also factor in the closing costs of the new mortgage to determine if it actually helps you.

What further analysis should I be honing in on and key factors/metrics/info that may be providing inaccurate numbers?

Meaning truly intrinsic(2x DSCR not 1x DSCR), then roll the dice and lever the minimum you need to get the deal done and understand to put more to reserves than anything else for the first 3-5 years from your current and new property.The risk:reward ratio is very low when you factor in a lack of liquidity.

By the time you factor in insurance and any cap ex....it's already a loser...even if you aren't carrying a mortgage.  

Insurance is just an expense to factor into your underwriting just like property taxes.

the key to investing in these types of deals is just like you just said.. you can lose the money and not change your lifestyle..

The house will need a new fence soon, so I'll have to factor that into the scenario.I'm not sure which choice is the best option for me.

Determine the most likely sales price of the build (factor in the cost of the land also) and include all selling costs to arrive at your net profit and ROI.