use -pxf1920 -pxf1080
you may need to adjust the vertical pixels (1080) to allow for the task bar

<t> As a total noob, I had to really dig in to figure this out. As the previous replies seemed a bit "fuzzy" I thought I would lay it out:<br/>
<br/>
Moves (m/c) 9/4 Fuel 214 / 50 (25) <br/>
<br/>
9 = hexes moved per phase at max speed<br/>
4 = hexes moved per phase at cruise speed<br/>
214 ...

Try -pxf1920 -pyf1280

- pxf/pyf are undocumented switches for non-standard screen sizes

This works for me out to 2560 x 1080