if anyone is thinking about doing this try and get all the items you need in the first 10 stages, then, just race to the teleporter on stages after that, start it and finish it then go around the map picking up the items. that way the difficulty level doesn't get too crazy before you activate the teleporter.
if you start having trouble killing stuff on stage 7 or 8 i would suggest stopping the run and trying again.
even on 'easy' its not that easy :-)