as much as I hate Mall-Terrains, they have awesome wear and are good going down the road....
as soon as you turn off the pavement and find yourself in a situation where you need a good off road tire, they fall on their face. Since this rig is primarily street driven I'd say go with the BFGs, as much as I hate them
It's hard to have the best of both worlds, the MTZs are a better off-road tire, but I don't feel they have the on-road characteristics you are looking for.
I have a set of TSL radials and I love them. They are the most aggressive "quiet" tire I have seen. For a tire with that much luggage, they are super quiet going down the road.