I've been playing around with something similar to make travellable landscape maps for my players. The key, I think, will be in the "Page Settings" tab for your map page, and specifically the Scale/Grid Cell distance partway down said page. This can readily be set to have whatever units are convenient for your hex sizes (for my travelling maps I have this set to multiple miles per hex). You may also need to actually adjust the sizes of the tokens (right-click on the token, then go to Advanced/Set Dimensions) to correspond with the multiple hexes a giant battle robot might occupy. Long Live Megatron!