House hack another property with a low down payment loan and use the remainder or the proceeds to either renovate or purchase another investment property?  

You'll likely want to evaluate the investment with UDFI tax figured in.The Solo 401k trust would make the payments to the seller/lender and would also pay for any investment-related expenses.

I currently have around 20k cash for a down payment and that is steadily increasing so I want to pull the trigger soon.I'm interested in Fort Wayne for a few reasons:- I have some family in the area (they won't be involved, but have some general knowledge of the area)- Decent schools- Low crime- Airport- Low pricesAny advice or connections are welcome as I am completely new to this.

I would strongly consider building equity to make a stronger down payment and further decrease your monthly cost. 

Tenant just moved in and is asking to delay rent payment until next month, looking for the 10 day move out form

One thing to be aware of is the FHA multifamily self-sufficiency calculation which determines if a property can generate enough rental income to cover its mortgage payments.

You payment is $2,600 plus tax and insurance.

I do not have to much cash for a down payment but was thinking of doing a HELOC on one of the rentals to get more cash and go the BRRRR method.

@Jonathan SniderFannie and Freddie do have LLPA's and the lower the down payment, the higher the cost.

He collects cash down payment and finances the rest.