In DPVRUnity plugin 0.7.3b or newer version, the plugin provided an auxilary camera mover script in Editor mode.
1. Open a VR scene, which contains DpnCameraRig;
2. Choose DpnCameraRig in Hierarchy window;
3. Find Asset/DPN/Scripts/DpnAuxiliaryMover.cs in Project window and drag it to the Inspector window so that it is attached to DpnCameraRig (In DPVRUnity plugin 0.7.5 and later version, this script is attached by default);
4. Hold down the Alt key, move the mouse around with the right mouse button pressed in Editor window to look around.