First, I’d make sure it’s a side loading machine - not a top loader with an agitator. Second, I’d have everything zipped up to minimize something getting pulled. That last point has to do with an attached bug net. I’d imagine that can be kind of delicate. It if were just a gathered end hammock with no net - toss it in. Unless you have heavy hardware attached to the ends. If so, maybe the hardware gets swallowed by a small bag or something so that it doesn’t bang around the inside of your machine.

When I started, I got synthetic quilts because of my water sports. But over time, I’ve found I could keep my down dry (good tarp, UQP, dry bags, etc.)

I did have one experience that was a bit sobering. It was in my tent days on the north side of Vargas Island - north of Tofino on the Vancouver Island west side. We woke to a mist that coated and saturated everything. All surfaces, outside the tent, were wet. If we left the tent door open, everything inside the tent would become wet too. So this was different than rain. Rain just comes down - sometimes sideways - and you can usually block it with a tarp. But this, this was like moisture on a search and destroy mission. Any surface, nook and cranny, it could reach was wet.

Not sure now a down quilt, even under a tarp and protected by a UQP, would fair.

But that was only one time (which I never forgot) in years and years of experience.