For Drag Racing
Bags are fine.
I had some pics of some drag cars with bags but can't find them. That being said, a big still works the same as a coil does but with variable spring rates.
With the trucks, run a 4 link rear end or even possible a 2 link set up. U can adjust the pressure in the bags to put the most weight on the rear wheels as well.
Some ppl complain they are no good for going around a corner because the state to firm the bag up u are too high. Most kits such as the Air Ride Technologies kit is designed to give the truck a 2" lower height at ride height. Combine that with 2" spindles and u are 4" lower. So even if u put more air in the bags, you are still closer to the ground the stock.
Now to go further. How many trucks have u driven in with 2" spindles and 3" coils ever drive real good lol.