No worries. I didn't know if you had gotten around to reading it.
So, since then I've been considering.
Stage 0 - Make it so the player has to kill everything outside first
Stage 1 - Mostly okay
Stage 2 - Give Boss a 10-15 second fire trail. Have it instantly kill any minions it comes into contact with. Have it spawn alternating replacement minions to the left, middle, right side of the path (alternating) every X units of distance/time. That way the minion count stays constant as well s the number the player has to be in contact with. The player then is weaving as he fights the boss and can't take the cheap way out and follow him.
Stage 3 - Still need Art or Transformation of concept
Stage 4 - Need to either spawn itself as minion or get Keith to change the boss lifecycle logic
Also, the flamethrower minions we can fix by reducing the range of the weapon by 50% to 75%.