Spray foam or steel wool.

Also are you renovating the bathroom(s)? Have

Howdy @Jason SterlingThe first thing you must do is determine the projected ARV as @Anthony Dooley and Thomas S. have recommended.  

This allows you to know up front if the Tenant(s) have a lease, security deposit, how utilities are applied, etc.

A few percentages have been shaved off, but nothing major.

I'd start by shaving my legs...

My understanding from a few sites is that someone experienced building with containers can shave 15-20% off construction cost and go up in less time than a traditional home.That said, I'm not married to the container idea.

I don't need new gutters but I am considering two different guard products: gutter brushes and gutter stuff foam.

@Adrien S. have you found a template/design that works well for post cards?

The extra insurance estimate and those misc. expenses should easily be $100/month.Now you have:The house hack scenario:monthly income : 625monthly expenses for the rented half: -312.50 (50%)P&I (your mortgage): -569.32PMI: -50cash flow: -306.82Cash on cash return: 0%Full rental scenario:monthly income: 1250monthly expenses: -625P&I: -569.32PMI: -50cash flow: 5.68COC return: (5.68x12)/((109900*0.035)+3000) = 68.16/6846.50 = 1%If your goal is to house hack and shave off some living expenses, it's not a terrible deal. $300 for your "rent" isn't bad and is less than half of what you're currently renting for.