A lonely bored dog will find a way to dig out to find 'fun'. Guaranteed. We had property on 4 acres at one point and no way could we fence the entire area - what we did was, using agricultural fencing, fence off around 1 acre so our hounds could be out there, safely CONTAINED - not that they were left outside without me being right there in any case.
And now you are talking about getting ANOTHER dog - when you apparently have no control over the one you currently own. No way - and there are, incidentally, no guarantees any two dogs will bond well enough to live together happily.
You say your poor neighbours are already angry about what your Lab is getting up to on THEIR property. Get real fgs.
ps Looking at all your other 'problems' with this young Lab - rather than starting to consider getting ANOTHER dog, you need to train the one you already have. Adding another will be forming a mini-pack who will get up to all the things your Labrador is into ..... doubled.