New construction has a a LOT more gotcha's for the inexperienced buyer then if buying an existing house.

I am interested in adding to my STR portfolio and helping my family increase the revenue of their existing investments as well!

Yes Helocs using bank statements absolutely do exist.

Learn how to to screen and select a quality property manager that won't cheat you or mismanage your property (they do exist).

Another option is to find a nice existing home and do a remodel to make it "yours". 

I am also negotiating a "Subject to" property with one of my existing clients.If you can get legs on the PM company (get to 200 to 300 units quickly), you should be able to have enough cash flow to be able to fund your purchases.If I were to do anything over, I would have quit my engineering job sooner and started in property management.  

If so, new service to the building would more than likely be required independent of the existing domestic water line.

The best first step you can take is to connect to a great broker with market knowledge and existing deal flow.

In the process of growing, we've reached out to existing STRs and LTRs to see if anyone was willing to do another arbitrage deal as we save up for our next purchase. 

It is still relevant but doesn't have some newer finance options like DSCR loans that largely did not exist outside of commercial banks until after the GR (Great Recession.)As pointed out, we in BP Nation don't know your financial means or your skills.