Have you looked at putting a horizontal scrollbar on your datagrid? Something like This will allow you to have many more columns of a greater width.
This can be done in 4.1.0 by setting a Class to the datagrid, for example wideGrid2000, then adding a section to your CSS file like:
.tundra .wideGrid2000 .mendixDataGrid_tableWrapper { width: 2000px; }
Hope this helps
Rotating text is possible, but as you said yourself this is not really supported by all major browsers just yet. I have had a try with it in IE 8 and it worked, but the results were really disappointing.
I used the following site to get things going. link