Flammenwerfer suits

Anybody have an idea of what color to used for the flame proof (resistant) suits used by the flame gun operators in the Sd Kfz 251/16? Working on the Dragon kit , planning on 2nd SS at 3d Kharkov. (And what would be the crew for one? I’m thinking 4. Driver, Commander and 2 gunners.)

Medium Gray or Blue Grey could be a start.