It's not a silly question! It's also been done! Check out this monster: http://www.thingiverse.com/make:41570
One suggestion I would make is that if you go bigger, plan to swap out the LM8UU y-axis bearings for the longer version. LM8LUU. This helps nullify any h-bot twist and prevents distortion on things like interior circles. In my current bot (which is standard size), I use 1xLM8LUU and 1xLM8UU on each side for this reason. I'll try to remember to post the bearing holders for the LM8LUU this weekend.