I wasn't particularly directing my comment to you. My facetious comments happened to align to your formula, regardless, I'll engage in a friendly debate with you anyways.
The J2807 test, which I am familiar with, is the industry accepted standard, and arguably is based on worst case scenarios. I'd further argue that J2807 is designed to approximate the infinite amount of variables in "real world testing with long distance or long duration travel". From the manufacturers point of view, there is no way they would build millions of these trucks rated at a certain weight without some degree of confidence that those vehicles will be able to accommodate that weight otherwise risking significant costs in warranty repairs.
You have unequivocally stated that the truck cannot tow its maximum rating extended distances without failure. I guess that is technically true, no vehicle can run forever without a failure. So I assume you have some data points in mind. What do you consider "extended distance"?
You have also specifically claimed the TCC as the failure point. You used the term "multiple" to describe the quantity of failures of the TCC that are directly attributable to "extended distances at max tow rating." What data are you referencing? What percentage is that fail rate of the total trucks built? What percentage is that fail rate of trucks that tow at maximum rate 100% of the time? Also, specifically, that the failure of the TCC is a direct result of the towed weight for a specified distance that is defined as extended.
I understand you forming an opinion that towing at half capacity may prolong the life of some component on your vehicle based on anecdotal evidence. By this reasoning, "the truck CAN NOT successfully" brake without wearing out the brake pads. Obviously, that doesn't make any sense. That's why ratings exist, so that we aren't applying arbitrary ratings that aren't backed up by facts and data. General Motors has access to failure rates of parts, operating conditions, costs, etc. that none of us have. Using that data along with specific tests such as the J2807 they have determined that the vehicle CAN successfully tow extended distances at max tow rating without doing damage. This is verified by their own publications: the owners manual has numerous guidelines about towing, none of them specify specific maximum distance at the already established maximum weight. Granted that "without damage" has to acknowledge that there is a failure rate of parts that will never be escaped. Again, these are machines that are not perfect, will encounter defects, flaws, assembly errors, etc.
I'm not arguing that your TCC failure may have happened as a result of towing at the maximum weight for an extended period of time. But it cannot be guaranteed that it would not have happened at the 50% tow rating you have chosen either.
To answer the original question, "would you feel comfortable towing in a setup like this with a weight distribution and sway control hitch or is this too much trailer for my half ton truck?" Is to provide an opinion of ones comfort level and a specific response to the trucks towing capacity, my response is yes and no, respectively. This is based on my comfort level derived from towing thousands of miles in varying conditions with several halt-ton trucks hitched to numerous trailers of varying type, length and weight. The second part of the question based on the data referenced above, General Motors published tow rating.