If memory serves, the game doesn't even define any base sizes or shapes. If you imagine all your models having 1" larger discs under their current bases, you could achieve the same effect (mostly) while using exactly the current rules. No big difference if you define a virtual melee range instead.
Technically speaking, melee range will create a slight discrepancy between movement (through small gaps, for example) and positioning in close combat. Also, it makes the combat arrangements slightly looser for, say, dynamite attacks. However, these details are currently very open to interpretation in the first place and hardly fine-tuned for anything. It's not a tournament game like Warmachine so you can do pretty much anything that looks/feels right.
Still, note that there's no model facing (front/rear zones) either. Using the original base-to-base rules, you can probably rotate the models slightly to fit. If you can't, I suspect someone's chosen too small a base to begin with...