Right, so, concretely, a fighter with a MV of 30 could charge from 20-30' (20' min. for charging; 30' = a doubled (running) half move) and attack on phase 1 or 30'-60' and attack on phase 2.
An archer being charged would definitely get a shot (or more!) off if the charge attack came on phase 2. If the charge attack lands on phase 1, then in a basic circumstance initiative would be the determining factor.
That said, and not to muddy the waters or get too mishnaic, I think there's a case to be made for adjudicating this through the weapon-length rules for charging ("When charging at a weapon-wielding defender, the combatant with the longer reach weapon attacks first if the WC difference is 2 or greater"). Missile weapons don't have WC, it's true, but I think one could easily say their reach is quite a bit greater than any melee weapon if one wanted to and just let them always go before a charge.
What think? Supported or just over-fiddly?
Also, we usually have a battle mat down on the table and some minis. We aren't real detailed about it, and I always make clear that the positions of the minis are Heisenbergian at best. The figures I use for monsters are totally not to scale. It all just serves to provide a sense of relative positions and eases some things for me and the players. We do use 5' squares for what it's worth