Rubber soundproofing on top of spray foam

[Anthrobus]

So I would like to insulate the front of my cab from engine noise using spray foam. It should bring it down about 10 decibels. I also want to put a layer of 10 mm rubber sound insulation mats on top of the spray foam and subfloor. I was thinking about trying to hunt down used rubber restaurant floor mats. Has anyone had any experience with this?