Over that thing I would prefer a good pair of Knipex adjustable pliers, way more useful than channelocks for getting bolts.
One thing that I really have to have for the portable toolbag is a vise-grip brand multi-tool, it has a hex bit socket, I keep a little set of metric sockets that clip into the hex in the same pouch.
So far I hate multi-wrenches, if I have to have one just make it a mexican toolbox, aka a crescent wrench. I do keep a ford wrench in the truck, use it more as a hammer than anything else. My oddest must have tool is a fencing pliers.
Now if you really want lightweight and odd places I would go for a bag of crows feet, an appropriate breaker bar, an extension or two and a uni-joint if you really have to reach crazy crap. If you cant get on it with that then it is for certain a Lockheed engineer thought it up.