Nobles would likely utilize mercs and gangs to fight their wars in the Rim while keeping their armies on standby in case someone tries something on their home turf. It wouldn't be uncommon at all, though to most people it may seem like random gang on gang violence, others might know it to be the result of nobles squabbling and insulting each other or simply playing chess with lives of others.
It would be more uncommon to see nobles go anywhere near the Rim personally but if they got it in their heads to try and expand their sphere of influence and take over a world forcefully it wouldn't be too far fetched. It's just more cost effective to use Mercs and Gangs.
But of course there would also be those Gangs that have no connections to higher class, those that just go mess with things because they can.
Galaxy is big enough for all sorts of situations, that's why I don't feel like explicitly saying one thing over the other. Sure a Noble might have a place of Residence on the Inner Rim where they might send their heirs to learn about governing and dealing with dangers of everyday life. They might even spend a lot of time there personally, but a Noble in the Outer Rim becomes much harder to explain short of an Open War or Pacification Mission. After all, who in their right mind would leave the safety and luxury of the Core Worlds.