I don't know if a feudal system is appropriate for a space faring civilization
I find this a very interesting subject, that could be turned into a question: What form of government is best suited for a space faring civilization?
There are some being related environmental variables that would have to be considered in answering this question:
1) What is the communication delay between the political center and the outer reaches of an empire?
2) What is the response time of central enforcement or military forces to the outer reaches of an empire?
3) For some forms of government, how much tendency is there for diversity of attitudes between the political center and the outer reaches of an empire?
4) Others. I just can't think of them at the moment.
For example, perhaps the speed of communication was limited by some factor, such as how fast a starship can travel, was the most influential factor. In that case, it would seem that a feudal form of government would be a better system. To get a feel for this, think about how the speed of communication on our world has changed over the last two to three centuries, and how the change in communication reach has changed how effective governance can be.