Hi Brandon,Not from Boston but a Double Barrel layout is better than an over-under layout.Less noise complements about footsteps overhead.If you build a Duplex, at some point you will probably wish you had built a tri.Bigger windows can make a smaller unit "Feel" bigger.Consider if they will make you use a commercial garbage service or allow you to have just regular pick up.Think about keeping the garbage area hidden (like they do at McDonbalds and etc...) it makes the property look nicer.Look into how many parking spaces they will make you have and decide (is that the amount you want to offer--or would more for visitors be a good idea).Look into fire requirement differences between duplex and tri--do they make you put in sprinklers, or fire escapes, etc...Spend some time with your architect and think about utility meter placement so it looks apartment like vs homeowner like (this could be a positive point on a sale vs rents collected).Consider having buried electrical service vs an overhead drop line if the neighborhood is up and coming.Just my 2 cents.

What are hidden cost factors and situations that a lot of newer short-term rental landlords make and what mistakes to avoid? 

Get the actual expenses pd from the sellers actual tax reports to calculate how much of that $600/unit rent goes to expenses... to calculate an actual Net Operating Income (NOI).The caprate for your zip code can be retrieved from a local CRE agent....Google estimates an average of 4.8% for the Charlotte area.That being considered, given absence of other hidden costs, this looks like a good deal on the surface.

Not every investor has the time or desire to search and underwrite hundreds of properties to find the hidden gems to acquire.

Investment Info:
Single-family residence fix & flip investment in Knoxville.

Purchase price: $40,000

Cash invested: $12,000

A single family home had significant fire damage from 2017. We bought...

I started with the shims that came in my kit and began just as the instructions said: attach the short end first, and then the long side.

Business: Form 3468https://www.irs.gov/forms-pubs/about-form-3468Instruction: https://www.irs.gov/instructions/i3468What is Form 3468: Investment Credithttps://turbotax.intuit.com/tax-tips/investments-and-taxes/what-is-form-3468-investment-credit/L886Wvvp5the solar energy property your business began using during the year on line 12b, 12c, or 12d—depending on when construction began—of Form 3468.

Were there hidden/surprise costs?

I think there are hidden gems but sometime stop and think outside the box.

If that's the case, can I get a personal loan from a friend of mine or a loan from my LLC, then, put a lien for $100k on the rental property, then, instruct the Title company to pay my friend (or my LLC) back the $100k when the house is sold?