IMO and no experience with DynaMat but the top layer is not a good base for paint of any kind; shiny smooth aluminum.
Downey’s idea of spraying on a deadener is the best thing, there are others though like Fat Mat; $80/gal shipped.
You can spray it with a 30/1 mix so it gets in all the little spaces, or brush it on. it is water proof if applied with good prep.
FatMat dries black, might be good enough if that is the color you want.