The Ravinok was never explicitly described as anything other than a "Cardassian ship" in the episode's dialogue. Dukat clearly stated that it was some sort of military vessel; indeed, one that was transporting a prisoners, suggesting that it was perhaps a prison transport, but nothing more.
Producer Steve Oster continued, "There was this huge, three-story mound of gravel in the quarry, and if you went up to the base of it and put your foot in it, part of it would come down," said Oster. "There was a lot of concern about that, and while construction was going on, we were constantly aware of it. We ended up building the ship on flat ground away from the hill and then just tapping the hill down onto it. They put the pieces as close as they dared get and then filled the mountain in behind it." Because landslides were such a real possibility, Nana Visitor's brief interior shots of inside the ship were filmed on the Paramount Pictures lot. According to Oster, "Construction said, 'We're not putting anybody inside this set,' because if the mountain goes –" Ultimately, the mountain stayed put and didn't collapse. (Star Trek: Deep Space Nine Companion, pp. 276-277)
According to Herman Zimmerman, "We had to imply that something the size of a Cardassian freighter could actually be located in this quarry [at Soledad Canyon]. And we had taken some big set pieces with us that we'd painted, no knowing what, if anything, we were going to do with them." Zimmerman explained that "They were about ten feet square, painted like the color of the hull of a ship. And one of them was just laying against this very fine gravel that looks like sand, and I thought, that looks like a piece of fuselage that's been uncovered while the rest of the ship is covered with sand. So we intentionally buried just those two pieces of ten by ten, side by side, and covered the edges with sand, so it looked like the side of a ship sticking out. We added a couple of wings and that helped a lot." (Star Trek: Deep Space Nine Companion, p. 276)