How can I satisfy iStock's .mov format requirements without downrezing my footage?

I'm interested in providing 1920x1080p footage from my EX1 to iStockvideo and pond5 etc. for sale as stock clips and I would be most grateful for any light you can shed on the following file format issue. Here is iStockvideo's FAQ on acceptable formats which is pretty typical for the prosumer stock-footage industry as far as I can tell:

Clips must be encoded with MJPG-A/B, PhotoJPEG, DV, or HDV, at BEST setting.
royalty free stock photography community | iStockphoto.com (http://www.istockphoto.com/videographer_6.0_requirements.php)

Using Vegas Pro 8.0b, I have rendered my EX1, 1920x1080p mxf clips to all of the above Quicktime 7 *.MOV formats (including MPEG-4 Video) with predictably shaky results except for HDV. The HDV render at 1280x720p yields the best looking results but obviously it's noticeably down-sampled.

These same original mxf clips playback perfectly from the timeline in Full Preview mode and they look good @ 1920x1080p when rendered as Main Concept AVC/AAC (*.mp4) - not acceptable to iStock.

I have looked at lots of iStock clip-info describing clips as 1920x1080. Can all these people be P2 users?

How can I satisfy iStock's .mov format requirements without downrezing my footage?