Aluminized mylar is almost as common as dirt, available in various reflectance/transmission ratios. I assume that the conductivity is too much where there *is* conductivity to begin with. I am making a wild guess that gold films on mylar are worse for conductivity even tho thinner films would retain integrity. So..sounds like you need to find company that can "nickelize" mylar or kapton, and is willing to do so on a sample basis. Maybe a pitch to bend them your way.."if you do this sample for me, i will make you the exclusive contractor for ((fill in reasonable info without disclosing farm)).