As far as a tow rig you do not have much to work with here. You are limited to 7,500 LB stock on the tongue. Hhalf tons for this year were never rated for goose necks. Generally intakes and exhaust improvements are not the best investment here. In any case the engine is not the major concern here. I would list the brakes as the first concern then the transmission.
I like moving, but stopping even more. If I want to pull around 7,500 to 10,000 LB all the time I would put a big brake kit on the thing. This would be the most expensive thing but your safety depends on it. Then I would put a good transmission cooler in. If you have gears less than 3.73's putting 3.73 gears with a posi in is the next step. Lastly, I would reflash the ECU and put a cam in matched to the reflash. Only then would I consider a low restriction exhaust. If you have some money left to spend get some gas shocks and overload springs.
After doing this a used late model 3/4 ton will look reasonable in cost.