The rating of the trucks takes all of that into account, so it's not like those components aren't capable - it's just a matter of whether the trailer is ideal for the truck's intended use. It's not like they rate the engine and glue everything around it; the cooling system, suspension system, brakes, and added options all factor into the towing and payload ratings. After all, "half ton truck" used to mean a truck that's designed to carry 1,000lb of payload - a new F150 has 1.5x the payload of yesteryear's one-ton truck.
That being said, I think what we're all getting at is that there's obviously a difference between towing a 36 foot long, 11 foot tall sail versus a 16 foot cargo trailer with a few yards of rock, even if they weigh the same. I agree with the earlier comment that 30ft and 8k lbs are good limits for what you want to even consider for a half ton. Even then, it'll do the job... but if you're planning on driving across the country or something, do you really want to be puckered that whole time? If you're planning to haul this thing all the time, just sell now while the market is good and save up for a diesel - towing big stuff every day is what the whole modern 3/4 ton truck was designed for. If you're only going to go to a local campground once or twice a year, that sort of occasional use is what your truck is made for.