A bit late to the dance here, but what I used were several 3M one and two-part products on my ceiling bows, strainers, pillars, and hood.
There are two two-part foams; the 3M #08463 is dark gray and somewhat flexible, and is closest to the material in your picture. Here's a closeup of some I dropped:
It is specified for precisely that sort of panel to panel and panel to frame element damping. It is OEM approved for use in collision repairs.
The 3M #08458 pillar foam is yellowish and quite rigid. As it's name indicates, it's target is filling the void in door pillars.
They both are self curing, so they can be used to fill voids where there's no air. That's *very* different behavior than the inexpensive canned foam sealant you get at home improvement stores, which will remain fluid indefinitely without air and specifically moisture to cure it.
They also both cure as closed cell foams, providing the skin on them remains intact. However, if you puncture or sand down the skin, they can absorb moisture, so it's best to apply carefully then leave these alone post cure! They are both paintable.
These foams do expand appreciably during curing, though glacially slowly compared to canned hardware store foams, so apply with expansion in mind, and allow for air and any excess foam to exit any cavities. If you don't, you could experience bulging of panels over the foam filled cavities as pressure builds! I saw anywhere from 1.5 to 3 times increase in volume, depending on application temperature. You can always go back and apply more if necessary; these will stick to cured foam, so layering is perfectly fine and is encouraged.
In areas where resonance was a substantial factor I used the 3M #4274 NVH ("noise, vibration, harshness") compound, which is a mass-loaded dark violet medium flexibility material, reminiscent of a fully cured dark colored RTV in appearance.
The dual plunger applicator gun is a 3M #08571. They could be had for under $50 when I purchased mine
-Yep, I also used it along the wheel arches, to help quiet down the walls. Even with all the strainers and damping, they needed a bit more effort.
It may be worth checking to see if the spot welds around the center of the ceiling bows are still intact if you're experiencing obnoxious amounts of resonance. Filling the gaps with any of these compounds will go a long way towards fixing, or even improving upon it, but is a seriously expensive option; the 3M products require an applicator gun, run around $40 per tube, and I used several dozen tubes in my maxi van.
The hood required clobbering power:
That being said, a large part of why I used so much is that I added 6 more bows and a similar number of strainers.
-There simply weren't enough original bows and strainers to quiet down that big ceiling and the sail-like walls; they only used enough to minimally support the structure. There's no substitute for a sound structure; I'd recommend performing structural upgrades long before wading into the world of CLD damping pads. Those lightweight bows and strainers do far more good than the heavy and costly CLD pads.
Peculiarly, and somewhat perversely, the region above the driver and passenger seats was especially ghastly; I had to call in a tactical nuclear strike on that area:
Now I can hear myself think...
I filled the additional bows with foam before even installing them:
Was it all worth it? See for yourself in these before and after examples of wideband spectral curves I collected from several of the wall panels:
And a couple of ceiling panels:
That's a lot of decibels of noise energy...
I hope that provides you with some additional ideas!