You will need to have big markers visible at all time while you are drawing.
I will add a switch in to the Editor for the extended tracking that vuforia offers.
That should give you more flexibility, as it tracks your marker as origin, even when the marker is not visible.
It will take some time for the App Store to review...
Eventually, once the HoloLens or Project Tango become widely available in consumer goods we should be able to reliably sense the visualization device in space. Then your example will be much better to realize.
We had many experiments to make better use of the iphone/ipad build in gyroscope and motion sensors in order to support scenarios like yours. The gyroscope works fine for rotations, but the motion sensor is no use for stabilizing translation movement.