CVEL Soyuz has one
The "CVEL Soyuz v0.4" add-on [ame="http://www.orbithangar.com/searchid.php?ID=1462"]CVEL Soyuz v0.4[/ame]
posted on orbithangar has two simple example payloads: Mars Express and, of course, The Probe.
In one of the included scenarios, Mars Express is mounted atop a Fregat 3rd stage. However, when I try to use this, I find that for some reason when I jettison the Fregat from the Soyuz 2nd stage, the Mars Express also jettisons from the Fregat, ruining the mission. By changing the scenario file to remove the Fregat, I did once manage to fly to Mars, though I had to aerocapture into orbit there.