X-Axis Date / Time tickformats... modify the default format?

[deltamelter]

I like the way automatic tick format only shows the time of day except for midnight and first and last ticks of the displayed range, where is will also show the date. The full date takes up too much space though and as seen in the example below, this means is is truncated unless I give is sufficient margin to spread out into.
I tried messing around with tickformat and dtickrange formatting, but these affect all visible ticks so if adding date or DOW, that shows for all ticks and doesn't fit well

Any ideas?