Any of the half-tons will get 8,000 lbs moving. slower than you would like? maybe.
The 6.2 and 5.3 are identical trucks except for the driveline. Even with the diesel, no real improvements to braking or control of your trailer compared to your 2013. The only upgrade would be more gears to match your speed and maybe feel a bit more responsive than your current truck.
you say 10-12 trips per year, how many miles? that's one weekend every month, I would say that's a decent towing demand. Your trailer is approaching the top end of what the 1/2 ton can comfortably do. Sure it works okay, but you are obviously concerned. What if you want to pull a boat or golf cart behind the camper, or add any more equipment, or upgrade the camper in a couple years? only you can guess what the future holds for your camping needs.
I would make the decision based on this: if you only pull it to the next county over, or 1 hour drive up north, then stick with the half-ton you like best. If you pull over mountains, and across country, you would enjoy driving the 2500 more.