You might be able to. You can certainly improve your towing experience. Air bags will help stability and make you more level. But they don't increase your axle rating or payload. A transmission cooler is cheap insurance to prevent premature transmission failure, but does nothing to increase towing capacity. You can do some transmission upgrades to improve shift patterns and have it run cooler, but it won't allow you to tow more. You can replace the rear differential which *might* increase capacity, but you may have to upgrade a laundry list of other things to truly increase the capacity.
Bottom line is that increasing the actually towing capacity is both expensive and time consuming. And in the long run, a bigger TV is probably not cheaper, but a whole lot easier!