Jedions brainstorm on what you can do with this

First off I have no prior experience with this before you brought it up. However, I did play an HS18 freighter load of Car Wars and even made my own arenas. In theory an arena game should be fun to play over and over but I don't think so in an RPG format. With Car Wars you got to try a new vehicle almost any time and then kept it interesting the only way that will apply here is new character each time . What I do think will work is first module opens with an arena combat much like Warriors of White Light started off with fairly mundane naval duties of ship inspections and about the third ship they encounter smugglers. So I would propose an adventure with ONE (or possibly two but most likely one) arena encounter and the adventure takes place while their visiting the planet for the event, the event is sort of incidental to the real adventure. Travelling to events on different planets is the pretext to have these adventures. Action is decidedly AD, not KHs. You could easily write a 3-4 module series. Each module could have one arena battle.