Not really new, during the soviet invasion of afghanistan ZU-23 towed gun mounts were lashed to the flatbed rear of ural trucks to provide serious fire power when needed... normally with no extra armour at all.
A smaller lighter jeep like vehicle with remote control rear flat bed mounted twin 23mm cannon would be a very good solution too... especially if the ammo feed was rejiggered to allow several hundred or even thousand rounds for each gun to be loaded in place in enlarged ammo magazines fitted to the gun mount so the crew did not need to leave the cabin to reload.
A smaller lighter jeep like vehicle with remote control rear flat bed mounted twin 23mm cannon would be a very good solution too... especially if the ammo feed was rejiggered to allow several hundred or even thousand rounds for each gun to be loaded in place in enlarged ammo magazines fitted to the gun mount so the crew did not need to leave the cabin to reload.