Required features for keying this out are insufficiently clear (and I think it is an early instar) and I am not familiar with odonate nymphs generally, but I'd suggest this is a gomphid. Given the location, most likely either a Yellow-striped Hunter, or Stout or Southern Vicetail, but I think the latter are more likely as the front end looks more like Hemigomphus that Austrogomphus.