Follow-up to this, all of this has been addressed with 0.9.2:
- Cam exiting can now open remote view at last position. This is a per-player toggle that's enabled by default
- The cam now shows itself as a giant GUI element covering the whole screen. Now it truly hides all base GUI, hovering over entities no longer shows the red selection rectangle, and you can't chart undiscovered chunks anymore, even though I think you should still see what's behind them