You can always overcomplicate the byes - At the moment I do not care how many Round 8 premos I have so long as I can field 18 players in Round 18. I plan not to trade in Round 8 but then use upgrades downgrades in Rounds 9 & 10.
That's probably the best way to go about it.
Some by planning should be factored in though. I found in previous seasons that the bye rounds, while tricky to plan for, are also the best rounds for making up ground in the overall rankings.