If you didnt know, you can make your own fonts. Have a look in the Renoise-Skin-Font folder.
I made a big and small pattern-font based on the 1.5 a4 font.
It has minimal background symbols to make entered data more visible.
The BigFont is also thin.
Hiding zeros is recommanded 
Give it an hour to see if this is something for you.
Download this file ,unzip and replace Pattern.ttf and PatternBig.ttf in Skin-Fonts folder.
cheers
use a true type font editor! e.g. Font Creator Program by http://www.high-logic.com/
I know. But unfortunately the symbol in between the Note letter and the octave number (the hyphen/dash) is the same symbol as the three hyphens you see when there is no notes (in default font).
So you are pretty much forced to use a dash symbol because of what you correctly pointed out.
I hope taktik could separate those symbols.
We could also wish for several font setups with different colours in same pattern to separate things better… but thats another story.
Pysj