A Cardassian ship might work better as a source of tension between the new XO and the crew……
I can agree with that statement; although I’m not sure why a Federation officer would be on a Cardassian ship. At this point, (post dominion war), the Klingons and the Federation have been allies for some time; and much like other nations who are allied, who often send exchange officers; a Federation officer on a Klingon ship seems more natural for me. I also freely admit however that I love Klingons, so am a little prejudiced towards a Klingon ship.
I suppose, a Cardassian ship, could work; if during the pilot episode they established what with the dominion war over, the Federation was somehow helping the Cardassian’s rebuild/the Cardassians asked for help from the Federation. Not sure though, I think they would have to come up with a plausible reason for the Federation officer to be on board