Building a sport court will run like $30 grand, but would increase your rental value. a 6bedroom 4 bath house with a sport court, hot tub, fire pit, mini golf, arcade etc. will most likely crush it because it's cool.

@Shelby Ek Do you need to activate the utilities in order to qualify for the loan you are getting?

BUT, get a solid quote on utilities.

In Chicago you request a CHA Burden sheet and that gross number minus utility allowance will be what you get in addition to making sure bedroom size is adequate.  

all materials, all labor costs to others, Not you, utilities, interest payments, permits, licenses, auto/truck expenses, tools needed are all deductable. 

Quote from @Fernando Martin-Gullans: Hey y’all, I’m a retail investor with 2 SFH rentals worth a combined ~$650k looking to utilize some of my stored equity to buy more out-of-state properties, but I’m not quite sure how best to proceed given that my interest rates are incredibly low (leaning me away from refinancing) and neither property is owner-occupied (which I believe prevents me from using a HELOC).

Would you be willing to describe a bit more about how you determined your utility caps? 

In many places there are some utilities provided by the municipality.

This property is gonna cash flow over $1000 a month after we're all said and done with utilities mortgage and more.

On utilities, I bought a foreclosure in NJ and found out it was not attached to Town sewer and I actually had to extend the main line up to my property then put the lateral in and abandon an old cesspool.