I used to keep a mitre saw (not the box, just the saw) in my truck just in case. I never have taken a rack off of a roadkill, but I did take one off of a forky that someone we knew had shot, lost and we found a week later (the coyotes had found it some time before that). I was thankful that it was a really cold snowy day, what was left of that deer was quite ripe.

I've actually driven by a couple on the highway and each time I chickened out only to find the deer gone later. It is illegal to do so in MA, and the only way to get a roadkill permit is if you hit the deer yourself.