Lets start at the back and work forward. The stock frame should be fine for just about any towing you can handle. These trucks are Chevys and are tough. The frame will have to be fitted with a suitable class III or IV receiver hitch assuming your trailer is a bumper pull. Once you find a receiver hitch that will match the width of your frame rails you will have to bolt it or weld it in place. I would suggest bolting using at least class 5 hardware.
Boxing the frame will not increase your towing capacity and is only necessary if you want a stiffer chassis for handling purposes.
The rear axle will be improved by going with a truck 12 bolt which are readily available in salvage yards with gearing of 3.73 or 4.11. This gearing will affect your mileage so an overdrive tranny would be wise for your daily driving. Whereas they did not come with disc brakes you really do not need them. Drum brakes work just fine. While on the subject, you will need to install a brake controller for the electric brakes that should come on a trailer of the capacity you describe.
Engine and trans will need to be up to the task in the torque department and have adequate cooling which none of the task force models were blessed with when it comes to high performance motors. Trans cooler and oil coolers will be needed.
Front end will be good with either the camaro or the IFS kit. I would go with the camaro subframe myself.
Good luck and send in pics.
