You know you can use the Ctrl+Backspace combo to go to the task switcher, right? I could've sworn there's also a go to menu, go to task switcher, and go to desktop option in ShortcutD (Which is what I presume you're using for your camera key shortcut). (I just tested going to the menu with browser in full screen with the menu option for shoft half press of camera key in shortcutd, and it kept the browser in fullscreen mode when I went back to it.)

Also, I actually can think of a way to use a dbus command in a power menu button to do what you want, and would be happy to help you set it up, but it only works if you have Matan's desktop mods (basically, if you have a modified hildon desktop package, like anything that allows for 9 desktops etc, including the one in the CSSU, it'll work. But if you're using the stock desktop, it won't).

Alternatively, I know there should be a way to do it without a modified hildon desktop, but I'd have to look at the source code of Shurtcutd, and possibly get you to manually install xdotool in order for it to be doable from the commandline (depending on how shortcutd does it).