Good luck running power tools on even a 5 gallon tank. If you break on the trail bad enough to need power tools, then you've done some pretty serious damage and that 5 gallons isn't going to last long. Your best bet if you're looking to run bring 'air' tools on the trial, is to look into electric. I love my air tools in the garage, but my electric impact is awesome offroad.
That being said... even when airing up, that tank is only going to help for so long before the compressor kicks on. And then at that point, all you're doing is replacing air as fast as you're taking it out. For me, I don't see the benefit of having a tank... especially in a TJ, where space is at a premium.
Edit: And a 5 gallon tank is pretty big. So you have a big tank on your Jeep that you can't do much with... just doesn't make sense to me.