In one respect, I believe that oil consumption is something to be aware of, IF it is happening, BUT as long as the "Add Oil" message does not display between changes, no big deal. On our parts dept fleet of GM pickups, using the OLM to change the oil (usually a bit past the 0% level), no "add oil" or change in oil pressure. Which usually is about 7500 miles the way it is being used. In the 6.0L box van I used to drive, I ran it 15K miles on one oil change once. I got the confidence to do that as at 10K miles, the oil still looked clean and was still at the "FULL" mark. Still "FULL" at 15K, too. All of this is on GM Dexos bulk oil.
The OEM oil recommendation is based on what was used to do the CAFE and emissions testing for certification. Therefore, the OEMs advocate the particular viscosities on that basis. But I believe that many AFM-type engines need the thinner oils for correct operation of that system?
I highly suspect there are no internal differences in an engine in a pickup truck, in a Camaro, or whatever. The more higher-perf vehicles might spec heavier oils due to the usage those cars might see, by observation. These "performance-oriented" vehicles might also have an engine oil cooler, too, which can figure into the whole viscosity deal, too.
Read your owner's manual and see if the "fine print" might have some alternative viscosity oils listed for special applications. Also, go through your Driver Info Ctr options and set the trans temp, tire pressure, and other screens you might be interestedin watching while towing.
I understand your concerns about a seeming "light" viscosity motor oil in a vehicle that can two trailers for hours on end. Also consider that the engine block and heads are aluminum, with a cast aluminum oil pan, which holds 8-9 quarts of oil. Which is not quite what we had in the prior small or big block Chevy V-8s (which usually held 5 quarts of oil, including the oil filter). Additionally, all of the viscosity recommendations have been validated by GM for any use the vehicle might encounter. The Dexos 1 Gen 2 spec is for a full-syn oil, whereas Dexos 1 Gen 1 was a part-syn oil.
Be sure to maintain documentation for your oil and filter changes, for warranty purposes. Which can make taking it to the dealer (or trust-worthy oil change establishment) for such a better way to ensure it's all documented, plus not having to dispose of the waste oil and old oil filter. Most dealers and such send information to CarFax, so any maintenance is documented there for future p0ossible buyers to see.
Those trucks are amazing. Enjoy!
CBODY67