For the longest time, everything I tried to prevent my hatch from rattling failed. Then I found that it wasn’t the hatch at all, but the sound bar. I simply loosened the top and placed three felt furniture pads between the camper floor and the sound bar and now enjoy one less rattle on board.I keep bedding up there year round, two sleeping bags spread out flat. I don't have a problem with the panels, when I pull them into place a little wiggling seems to drop the cushion into it's place too. The rattle I get is with the top and the sound bar all winter long but when I put the kitchen in the back and add some weight below the noise stops.
I'll add that we mostly use a ladder to get in from the outside so I don't use the hatches much unless we're in a spot I don't want to use a ladder or it's raining. With two people you can use the hatch but it's a yoga workout getting in and out with someone in the way.