The Snap-On 18V cordless impact gun only weights just under 3lbs with the battery. The tightening torque is 284lbs. That is plenty of power for the trail. The air impact average from 250-450lbs. I have an IR & the removing torque is 650lbs. I use it to remove cylinder head bolts from diesel engines. I don't think anything on a Toyota get torqued to 650lbs 
I don't see neeeding this much power on the trail. Just my 
I try to make everything i have do at least two things. York onboard air gives me air for my air rachet and impact, airing up tires fast, i can swap a tire fast in the freezing rain, i can paint a shed on somebody's back 40, i can run ARB airlockers if i had them. I carry a cordless electric hammer drill cause air drills consume too much air and the cordless is more portable.
If i'm on the side of the road with a flat, with the girlfriend in the truck...it's cold and rainy, and i find the spare is flat, i can jack the truck off the ground with air, plug the spare or the flat, air back up without waiting forever for my little electric compressor to inflate my big tires, and be driving. My air system doesn't rely on a CO2 supplier...the powertanks last a long time but when their out, yer screwed. When i get my genhead on my 22R, and i can run my 220V plasma cutter on the trail, i'll need onboard air for my air supply.
