My monthly mortgage payment will be approximately $2,100.Comps in the neighborhood are currently renting for around $2,600/month, so my plan is to live in the property for 1–2 years before renting it out.

Mortgage payment is $1671/mo. 

Then use the extra roommate rent income to pay down your mortgage and look to refi to a lower payment in the future (3-5 years) - so it cashflow when you move out.You could also choose the smaller unit and STR the other unit to generate more cash to pay down your mortgage and refi, so it cashflows when you move out.Bottom line: you'll have to get creative to solve your cashflow challenge!

Spend the time now reading and learning so you will be ready when you have the down payment for your house hack.

How do you find a good contractor to where you can trust there estimate?

You can also take advantage of lower down payment loan products rather than going 20-25% down on a conventional investment loan. 

Down payment: Can you give us some of your reasons for wanting the larger down?

Cost Overruns: After the final payment, the contractor claimed there were additional costs of $60K.

Quote from @Jeff Brogan: I would hire a trusted expert to get you real numbers, someone that does it in that area all the time (rents out properties/property management). 

To scale, I plan to build a reliable local team, leverage 25% down payments, and use strategies like HELOCs or cash-out refinancing for future acquisitions.Good luck!