|Nor have I seen the foams you mention anywhere................  Interestingly neither Dow or Owens Corning list the density for any of these two families of foams.

Yes they do.

http://www.foamular.com/foam/products/foamular-1000.aspx
http://www.foamular.com/assets/0/144/172/174/98cf58e1-c3d2-4b6c-beb5-2063215bea18.pdf

https://www.dow.com/en-us/building/industry-updates/top-6-questions-asked-of-rigid-insulation

If you can't locate a supplier locally, try harder.