It sounds like a heck of an idea. Ive done a lot of coyote hunting in MN, we dont have those long desert shots and we have so much dense cover here that the coyote just act different than they do in the open plains or deserts.
For me, coyotes come in fast 70% of the time, almost all my shots are on a coyote under 100 yards and I have to bark at it to get it to stop moving, that would make 500+ yard shots near impossible.
Im just thinking out loud of how I would approach this, I havent tried it. But I think there are two cases where this long range could be made to work. I would set up a call opposite to how I normally would, normally I try to get the call in a low spot or dense brush with a clearing around it, I dont want the coyotes to see the call, I want them to have to run up to it to find out whats going on. Out in open desert, you could set the call in the open, where you can see all around. The idea is that you want curious coyotes to show up but calmly stop far from the call to look at the strange sounds right out in the open, they are very good at knowing the location of a sound from very far away. If the call is in dense brush or in a low ravine they must come look or use wind and they will keep moving until they see it or smell it, if the call is in the open and they can watch, they will stop and watch.
Second approach would be wind, very windy days. For me the harder the wind is blowing the further down wind a coyote will circle and the more certain that the coyote is going to rely heavily on its nose. On calm days the coyotes can approach from any direction, on windy days the coyotes are going to be coming from down wind or they are going to be heading down wind trying to get a scent. Its going to be tough shooting at long range on those windy days but thats one case were further call distance can be a big help.
The most important part is getting the coyotes to show up but keep them calm enough to stop and allow long range shots. I took my30" 260AI one day trying set up "long range" shots, MN doesnt have long range... I got a couple coyotes to show but it was like aiming an artillery piece at a pheasant.