There has been a ton of mis-information here on how to use Happi-Jac turnbuckles correctly..
From the horses mouth:
For the front turnbuckles,You want to tighten the front turnbuckles until the slack or wiggle is out and the turnbuckle is snug. Put a mark on the hook opposite the threaded rod next to the barrel. Tighten the turnbuckle until a quarter to three-eighths of an inch of the hook is pulled out of the turnbuckle. This compresses the spring giving you about 300 pounds of pressure. Tighten the jam nut to keep it set.
For the rear turnbuckles, also tighten them until the slack or wiggle is out and then tighten the jam nuts to the bottom of the barrels. The purpose of the rear turnbuckles is to keep the camper from bouncing up and down. The side to side movement is controlled by the front turnbuckles.
I have never used the TL system but it sounds like the O-ring would be a small plus and they both seem to need the same twisting and turning unless you get the quick loads or derringer addon which I have been thinking of doing for mine...
It is time consuming if your in a hurry to twist and turn to have the 300# of pressure recommended.