My brother and I do a mock - 4 years running. We account for trades by not assigning a team to the play. Ex. Pick 1 Jake Long, Pick 2 Glen Dorsey....ect.
It works pretty well. We live in different cities and use food as a prize. I live in Oakland. I win, he ships me wings from Buffalo. I lose, I ship Dungenus crab from SF.
Fun times. Enjoy your draft day!