Related to the topic of gameplay structure, what about incentives, rewards, and encouraged behavior?
With characters in these kinds of games typically opperating a space ship, and combat equipment often being highly customizable, there are lots of opportunities to spend money to the point that PCs will probably never run out of things they would want to buy if they could afford them. Which makes money a much more useful long term incentive than in most fantasy games.
However, many games also have some kind of exprience points as a secondary resource and reward that makes characters stronger, more durable, and might even gain access to new powers.
A good XP system in any RPG provides players with XP for behaving in the kind of ways that are considered typical for protagonists in the kind of fiction the game aims to mirror. Since players never say no to opportunities for more XP, they are generally quite happy to go with the option that is promising XP when they have to make a choice what to do next. Without the GM giving any kind of nudges what the players should or should not do, in the long term such XP incentives lead to the rewarded behaviors becoming quite common. And the players will enjoy action somewhat strongly stereotypical even when a game with a different tone would be just as possible. At least if the players are buying into the initial premise for the game.
The more codified the reward system is and the less it depends on the GM's subjective approval of the PCs actions, the more control the players have to judge for themselves the rewards and risk of their possible actions. In the most extreme case, if players have no idea what behavior will get them XP and how many, XP would not work as an incentive at all. Particularly when going for a kind of sandbox campaign, giving the players the full rules of how their characters will make XP is a very helpful tool to enable proactive PCs. Knowing what kinds of things would get good XP greatly reduces the tendency for decision paralysis.
In a Space Scoundrels on a Starship adventure, what kind of quantifiable actions, behaviors, and accomplishments would we want to see from the players to create the tone of this style of fiction?
Combat certainly is a common feature, but I think just as important is the daring escape from overwhelming foes. Giving XP for defeated enemies would encourage staying around in a fight much longer than serves any point in the narrative because it would get the players more XP than immediately jumping into their vehicle and speed away.
Similarly, since money already has a great value in itself and can be directly translated into more combat power, tying XP to money gained doesn't seem very useful either.