While this is an overall great design.. I feel that while it's standing vertical, unless there is some kind of back piece there will be too much strain on the power cord connector and either the cord or phone (or both) will break with what i see of the current design... So here is a question.. In the last picture with the cover for the cord insert, will that be steady enough to hold the phone upright and stable? or is that JUST for covering the cord and holding the cord in place?
Never mind.. i see that you added a nice bit of diagonal backing to the design... that should be enough for vertical stability. I like it even more than the first design.
The cover back don't have a mechanical fonction. I just realised this removable part in order to cover and to hidde the cable. It's just for a better visial aspect but also to avoid a very big hole in the dock for insert the cable.
If you don't put this part your phone will be stable in vertical position.
I would post some real photos when I will receive the dock.
Just for information, the outline and the back of the dock is 3mm thick. So it's strong.