Real estate investing and flipping has become increasingly popular because of the return on the investment and the ability to use other people’s money to do so with the intention to increase both parties return.

This increases your NOI immensly.

Fixing it up to increase value with no money difficult.

You will probably see your HELOC rate increase again in the next few months. 

I should mention there is some room to increase rents to the absolute max it can get, which might backfire.

Your decision is based on how much it will increase the rent. 

Take a look at your financing package and understand what your total annual increase in net worth is.

However even if I increase utilities, vacancy, capex by 5% all around, I'm still near $300/mo.

Also during the ownership you can increase the value by improving the property and getting your feet wet.

Everything else you mentioned, like improvements and Section 179, are basically ways to increase depreciation.