I remember at CIV in Los Angeles, we were required to check in our "weapons" and have a florescent green "tie" placed on it.
As in Hawaii, California has a very strict "replic guns" law. At our yearly Kawaii Kon, a "tie" weapons program is used to account for our blasters.
If you don't mind the hassle, I'd fabricate an orange-colored plastic tip/cap that you could screw into the barrel of your E-11. When you're in a more "blaster friendly" environment, you could unscrew the orange cap and stow it away.
I have to admit that taking pictures with orange-tipped weapons is lame but events have rules and regulations for public safety.
T