Opera is hardcoded to install to device even if you specify Internal Storage. See this thread for more info:
http://forum.ppcgeeks.com/showthread.php?t=39478
Nonetheless, stopping the customization and installing everything you can to Internal Storage will free up a lot of space. I have almost 49 MB free in storage memory now, even with Opera installed to the device. And of course the tf3d web tab still works as well.