I found an excellent extender, after market, for the two cameras where there's a need to get your nose off the LCD screen. It's about time someone did this.
This one is available on Amazon and on eBay for about the same price of $15, which is very good compared to the OEM piece...if it existed. The advantage of the Amazon piece is that it comes with a microfiber cloth for use anywhere.
This one comes in two pieces, which in the picture are assembled. The outer piece is almost identical to the OEM Canon eyepiece. The inner one, next to the camera body, contains lenses that will distort and reduce your view. Combined, the two pieces are about 1 mm thicker than the Canon EP EX II and eyepiece combination which I have on my 5D2. The extender really takes your nose off the LCD on both the 7D and the 5D3.
I found the best way to use it is to slip the two pieces apart, and remove the two Philips screws that hold a shim which then holds in the lenses. Pop out the lenses, throw them out, and reassemble with the screws and re-slide the pieces together. You can easily still see all four corners of the screen without any size reduction or distortion.
I put two small pieces of gaffer tape between the two pieces of the extender, and on the back of the extender piece which touches the body. That really stops the movement of both on one another, and makes a really firm extender, that can still be removed from the body if you want. Use gaffer's tape, not duct tape. The latter has glue that will stick to whatever it's on when the tape is removed.