I’ve encountered the same problem and have a partial somewhat contrived solution. It allows me to get a little more than 1kb of text from sandboxed Internet Explorer instance.
I use http://goqr.me/ to create a QR-code from the text. Create it in greatest possible resolution and open it. Take a screenshot of the window on the clipboard by pressing Alt-PrtScr. Then I use a small utility (see https://github.com/thoraage/qrscanner) to extract text from the picture on the clipboard.
It is a sick world!