I've had my rig set up nearly identically to yours Steve, for a over year and probably 30kmi
I don't "off-road" ever, due to the nature of how I have my chassis and suspension set up (full sway bars, caltracks, poly everywhere= NO FLEX
but I'm known to travel logging roads faster than most
I haven't had any issue with the frame stop slapping the LCA, I have heard it happen once or twice tho, not enough to feel it, but I knew exactly what it was. Happens in downtown Seattle, when you're heading up the steep hills from the Sound (Sea level) and you transition from hill to the level thru street/cross street, back to the hillside, at each intersection...lol
But only if I'm going too fast
James had a great idea for me once, to get a small universal bump pad from energy suspension, like the ones Cognito uses on the UCA package...
Never bothered with it