Catching up on people's theories:
I see renewed discussion of the white truck, and distorted stills from someone's big-screen TV.
1. Regarding whether Mickey is seen on top of the truck - no. All you have to do is look at the original photo (not cropped/enlarged), and it's clear that there is not a person on top of the truck.
2. What looks like something draped over the right-rear window looks to me like classic lens flare, combined with one of the jagged vertical breaks in the still that LE released. If you compare the pic of the DWT heading right, and the DWT heading left (both at Circle K), you can see the same area of white oversaturation on the rear window of the truck heading left. Looks to me like a light source that reflected off the rear part of the roof of the truck heading right... then was both distorted by the vertical break in the still - and then spilled over through the lens-flare effect, to look like something (a tarp, etc.) hanging down over part of the window.
If you want to see what I mean, look at the picture of Mickey coming toward the camera on Versailles, then look at what looks like a big white blob ahead of Mickey. I and others have compared this blob to night-time photos a WS poster took, and agree that it was created by the bright lights of the bus overhang to her right. Now look at how the light appears to spill around the front side of the 25-mph sign, even though it's not really doing that. This apparent spillage made it look almost like LE had whited something out in the photo. But the more I looked at it, it became apparent to me that it was a lens-flare effect, falsely adding a white smear to the front of the 25-mph sign that really wasn't there.
I believe that this same effect on the 25-m.p.h. sign created the optical illusion of something hanging over the right-rear window of the truck heading right (following Mickey), when it actually wasn't there. Lens flare can do weird stuff, and then when the picture is blown up and the contrast altered, it can look like something it isn't.
3. It seems that BL's m.o. would have been to take someone alive. Note that BL didn't kill his 1999 victim. It would have taken one heck of a high-speed hit to knock Mickey up onto the hood or roof. The fronts of those trucks are tall and vertical and higher than the bike and rider. I doubt that a bump that only bent the back bike rim would have thrown her up there - and I think that at that speed, the bike would have shown a lot more damage. And if he wanted to take her alive, then a hit required to actually knock her up that far would almost certainly have had to be high-speed enough to be fatal, and so why would he hit her that hard? Seems to me he would have wanted to hit her hard enough to knock her off the bike, but not hard enough to kill her outright.