My main point was this needs thought about or the little things will slip you up.
Getting the building isn't really the hard part. It's all the heavy earth moving you mentioned. Or rather, hiding the earth you're pulling from the tunnels.
If it's not Barrens - or even if it is - actually turning it into a working brewery is probably a better option.
hmmm. Buy the brewery that's actually IN the barrens, and turn it into a working brewery. First, it justifies the first layer of security just due to location: wire, sensors, a bit of security force. Second, your excuse for digging gets easily justified: you're making a secure and temperature stable storage site for your beer (or distillates if you want to go that route) for aging. You can even build a reinforced access tunnel for transports.
The working brewery/distillery also gives you cover for bringing in goods. Regular truckloads of grains and such, materials for the labs (yeast development, gruit development {an alternative to hops}, etc), you get the idea.
And if it happens to make a profit, that's just a bonus.
The downside, of course, is that this creates an infiltration point. On the other hand it's an avenue you know and can watch.