Hi all, thanks for the discussions on this topic!
I've come to realize that as long as space is not really an issue, I should take advantage of the short duty-cycle of the problem by splitting the current-driving and the boosting into two separate circuits and putting a larger capacitor in between them. This way, the boosting supply only would have to supply say 500 mA / duty cycle, say 15, which is only around 30 mA, easily in range of most circuits. Then a traditional current-driver would tap the capacitor when needed for a flash.
This is not as clean and nice as the other solution, but it surely reduces the ratings on the inductor and other components!
I sure learned a lot about switching supplies while reading all the application notes on the regulators out there :)
Regards,
Bjorn