As a side note, and not the most effective way to create distance. But EQ can play a part. I've ever used it for that reason, but I'm thinking that something far away might sound further away if the highs were cut, but it's not something I've ever experimented with.
I also have not deliberately messed with EQ as a localization tool...but I seem to recall reading something ages ago about the whole Left/Right, Back/Front, Up/Down manipulation of the image space...and that for stereo, L/R of course, is easy with panning, Back/Front (or close/distant) can be manipulated with dry/wet processing, which can also affect the L/R if you use a stereo reverb that can also be panned.....of course, levels also play into it...louder always feels more in your face....
...but there was a comment about the Up/Down, as the hardest for stereo systems to create, but that EQ could help give some location information. I think the info said that the highs for Up and lows for down, which seemed to make sense.
Funny thing, the song I just did as a duet with a female vocalist, with both our vocals panned center in the stereo image, her voice just seems to be up above my baritone voice while in that center panned position. You can actually get the sense that it's higher up in the space, so there seems to be some validity to the EQ thing, though as I said, I've never deliberately tried to use it for localization of sounds, and you may be right though, that it also can work for the front/back placement in conjunction with delay.
For more precise placement and feel, you can also record stuff with all stereo mic techniques, and during tracking place your source in its position in the image.
Bruce Swedien did a lot of stereo tracks when recording MJ's albums. It's one of his signature recording SOPs.
I'm sure it takes a lot of good planning and thought to position your sources in the L/R image during tracking, so that it all falls into place during mixing, but I think that's a way to get some nice textures that mono-panned tracks can't.
I've wanted to try it on a song....but never got around to it.