We are considering renting a home in the neighborhood we are interested in buying in, to test it out for a few years.

Well worth the extra cost to have a product that lasted 30 years.

We project we would still be cash flow positive even with the extra costs of the HELOC, but we would ideally rather have more cash flow then less at this timeWhat are things we need to be considering or thinking about?

I'm not trying to rip into the work and expense you've done, but for not much more per night, I can get something really great with more bedrooms across the street in Championsgate, Windsor or Solara.I'll jump in about the grill too, that's way too much, especially since your title says "Pool & BBQ", but I have to spend extra to get the BBQ part.

Did you buy with the intention of doing STR?

Buy a property worth at least a million, better a few million, to make it worthwhile.  

It looks like you are not able to get lending because your Debt-to-Income ratio is too high.You should figure out what your DTI ratio is.If you are buying cash-flowing rentals, your rentals should actually be helping you get future loans easier.

If it is section 8, i would make sure they at least have some income coming in to be able to afford to eat, clothe, and buy all the other necessities. 

You'll also need storage space for cleaning supplies, change of linens and towels and small miscellaneous items like a first aid kit, extra batteries, flashlights, broom, vacuum, etc.

They tried to compensate for this by providing me with an extra list to call which I appreciated but even that proved to bring barely any more lead flow.