double-bubble foil mylar insulation for boats?

https://www.amazon.com/dp/B081VPC8W...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

I'm planning on using this stuff on a van. They say its supposed to be sort of "loose" (not sprayglued directly to van's metal walls), then can be covered or not. I'm thinking of using good double-sided tape on about 10% of surface to hold in place, and see what happens. Plan F would be Hot Glue Gun.

Or I might run string through little holes in van framing and insulation and 'sew' it in.

Might finish van interior with 1/8" door skin or 1/4" plywood, or Plasti-Core, or might not. I kinda like the idea of reflective material helping the interior lighting. Also occurs to me I've never seen that used in home, office or RVs. I'll let you know it if causes mental problems.

I've never seen this stuff used on boats, just rigid (mostly pink IIRC) slabs of foam between metal hull and finished interior.

Would this stuff be OK for boat? Seems like it could be good for otherwise hard to insulate compound curves and allow work to be done wiring and plumbing, etc.
Could this stuff be used exposed to focus heat (and light) on certain places you want to keep extra warm and dry, like bunks?

PS-I'm also going to try making a "bivy" out of this stuff. It will be two 8'x4' sections, with bottom section upturned to form 'bathtub floor' and top section edges down turned to fit over tub rims to shed rain. The material is not 'breathable' but for this application I'm hoping condensation would be mitigated by insulating/reflecting and all around venting. Not sure what and how I'll make various connections and still keep top 100% waterproof, and keep everything easy to use and get in and out of. Ideally, the two sections could also be deployed as an 8x8' tent or tarp or a section used as a fire-heat reflector.

 

It would be interesting to see how much difference 1/4 inch of insulation will make. Obviously Soundown or equivalent in a thicker material would be better but at many times the cost

 

Soundown website only mentions sound insulating properties. I'm 95% concerned about temperature and any noise reduction is merely OK. I used one-sided foil faced fairly thin HVAC fiberglass material under homemade wire mesh secured with 1/8" through nuts and bolts to insulate (on the inside side) the engine box of a mid-engine 1968 Dodge 108 van and it worked amazing, both sound and temperature...but I don't want nasty fiberglass leaking into the living area of the van. I like to use a garden hose and spray nozzle to clean out the van and let air dry to stay hygienic, and I think the bubble wrap will be OK with that.

 

I used this stuff on my boat in the cabin top area. The existing furring strips place were 1/2" thick and I made cedar planking strips. These were screwed into the bubble wrap and furring strips. The compressive nature of the planking and screws create a very good seal.

Did it work? i don't really know, my cabin top is foam cored but I feel like it did.