Layering down quilt over synthetic?

If down is on the outside, it will get compressed less which is good

if you’re 0-10 F, water evaporating from your body, might migrate through your insulation and encounter the point where it’s 32 F inside the down layer, and then freeze there

That would be more of a problem on multi day trips

you could try it, weigh both layers, before and after, to see if water is accumulating

Yeah  I’m aware of the few point issue. I’ll be doing weekend only trips for the fall so it only has to work for one night. Looks like I might have to be the guinea pig on this one.

Just a point on fit:

Won’t the BPL quilt  be too tight and compress the down?  Especially in the footbox?

Either way, the water-resistance of the down should work as advertised – so try it out when you can and let us know!

Youll find that the down will get somewhat damp

how damp it gets depends on the conditions, but over several days this can be a serious issue if you dont dry it out

with DWR down this might be less so … Who knows

you can order the materials and make yr own synth quilt for ~ 60 dollahz

;)

“I’ll be doing weekend only trips for the fall so it only has to work for one night.”

Not worth worrying over then, IMO. I used a 50F quilt inside my 30F one(the two together weigh less than my EN 10F bag) without issue for an overnighter last year when it was 4F both before bed and in the morning, and could feasibly have gone lower during the night.
Same reason as you-both “wide” sizes with Hyperdry 850 down, but my 50F is shorter and narrower than my Katabatic 30F, which attaches to my pad, so using the 50 on top would not have worked as well. Surely not an issue at those temps for an average sleeper(for whom that system would likely be marginal, at best), but I actually got a little too warm for awhile, and it was nice being able to push the 50F to the side while still cocooned in the Palisade.
I used mine for a pillow that night, but at those temps you should have a warm puffy along, too, and be ok at 0-10F even if your quilts aren’t quite up to the task.
Have fun experimenting!