I feel the game should have ended after the epilogue. It really doesn't add up to settle down one moment then come back to playing a pre ending game state. I understand its probably done with the addons in mind but it kinda ruined the absolutely brilliant tone that was set for 100+ hours.
I plan on completing all the side quests on my second play through before finishing the main story. The whole non-continuity of the post-game sucked out all desire to finish the side quests / contracts I still had on my first play through. Probably is best to treat the epilogue as the end of the game, and the whole post-game thing as just a way to dinker around.