Instead of Toowoomba, what about Oakey? Small township about 40km inland from Toowoomba. A lot of people commute there from Toowoomba for the Army Base (including my DH a few years ago). You also miss the worst part of the Warrego Highway where a lot of the incidents occur.

Basing yourself there, you would cut done commuting time for your DH and still live in a relatively small town. Yes, the Army Base is there but I don't think it is too noisy as most of the big planes (like the C17 and the transporter) are based at Amberley.