Holy...
That took me, like, what, a hundred attempts?.. Before I saw your comment and won the game after LITERALLY the first try of this strat. It appears to be so effective, that I didn't even need to collect the ''Haste'' and "Two extra ammo'' powerups.
Thanks A LOT, man!! I don't know, how many more tries it would've taken me, if I would not have seen your comment!