What I normally do when I know I need to heal a group as an AST that I can't reach because of the reduced range is to pop light speed, and run to each group so that it's not an issue. I know it's more mp, but a good group tends not to need it, also you can catch up on some of the damage if the DPS is handling the adds properly by popping collective unconcious at each launch phase, the cooldown is just long enough to pop as you are all running from the aoe pulses.