Where to mount rear plate?

[GreyHoundSteve]

I bought my 67 with a rear rollpan that does not have a place to mount the rear license plate. Im in TX and i know that i couldnt make it 10 miles without getting pulled over without a rear plate so my question is this; Does anyone make a plate holder that mounts to the rear window or something? I'm also open to other suggestions as well. I had originally planned to just replace my rollpan with one that has a plate holder but the rear of the truck looks so clean without it. I thought if someone made something that could be wired for lights and mounted to the rear window that would be my best option since the space behind your head is useless anyway .... anyone know who makes something like this and where i could find one?