As long as you have Towing Mirrors fitted on Both side, then I think you will be OK.
I do not have the E marked on my mirrors, but I am not going to purchase a new set, due to some scaremongering from Milenco.
If I ever get pulled up about them, tnen I shall plead ignorance, as they are not a permanant fixture of the car and I have better things to do in life than source legal documents, as to finding out the can and cannots,
Best regards, Martin