The mentality of 3.08 = bad, 3.73 = minimum 4.10 = good is still very pervasive around here. Folks, with the current batch of 6 speed transmissions, the axle ratio is far less important, allowing mfrs to offer only 1 or 2 choices. The 3.08 with the 6 speed (3.08 x 4.17 = 12.84) is STILL deeper than the old 4 speed was with 4.10s (4.1 x 2.84 = 11.64)!! The closer gear ratios keep the engine in the power band (which is higher than old big blocks) Yea, double overdrive will be useless for towing, but is why the truck gets 21mpg unloaded.
The issue with 1/2 ton trucks has never really been about the power, it's about payload. Both of those trailers seem to be at the sweet spot for 1/2 tons, about 5k dry.
If your Silverado has the typical 1500lbs of payload, subtract off your 4 passengers at say 150 a person for person and stuff for 600lbs, leaving about 900lbs payload. Divide by 14% which is typicsl tongue weight for a TT to get about 6500lbs fully loaded. Subtract off water, propane, batteries, food, and stuff. 5000lbs dry is a good number to look at. Both units would likely work out fine. And since you have a truck you have a longer wheelbase to help with the length of the trailer.
Long version of what ATP said :)