ManyMag, as Weekender mentioned, place your bait site at a distance you are comfortable with. Mine is only 60 yards from my little cabin and I have taken a bunch of coyotes at that place. The further away you place the bait will lessen the chance of being heard from making any sudden noise, but also it increases shooting distance which may require some more precise aiming / shooting.
If you have a building of some sort to shoot from, distance can be shorter. A building, in my opinion, is the very best way to bait hunt. A small storage building can be converted into a hunting shack or a small building could be easily constructed. It can be insulated, heated and have a warm, comfortable bunk that will allow you to settle in for an all night hunt. Mine is an 8x12 foot.
Coyotes can come at any time, but I have found that they generally come to the bait at night, so being able to stay the night is key to any real success. As long as you are quiet you shouldn't have any problem with a bait site at 50-60 yards or so when shooting from a building. If you are out in the open when shooting then personally I would want the distance to be greater, and as you mentioned, being cross wind would be the key, but even then the wind can change direction and ruin a hunt. It could also be a very uncomfortable night if sitting at a bench for any length of time.
Here is a video of a coyote I took at 60 yards, shooting from my little hobo shack of a cabin. You can see it near the end of the video.