It is actually possible to play all three guys a lot. That is what I think will happen. If Osby gets 20 minutes at PF and 10 minutes at the 3, you can play Osby, Clark, Fitz and Arent for 30 minutes a game. (120 minutes for 3 positions). I will be shocked if it averages out to exactly 30 a game but having all four guys average between 34 and 26 a game is very possible and likely in my opinion.
If you get production as follows:
Clark 12 points, 4 boards a game (which is only slightly better than what he did as a freshman - he averaged 4.5 boards and 9.3 points on the season but I don't think adding 2.7 points a game is a huge stretch)
Osby 12 points, 6 boards (if he is as good as people say he needs to do this)
Fitzgerlad 14 points and 6 boards (only 1 board and 2 points more per game - if they guy gets to rest and does not have to worry about fouling out so much I think he will improve his stats)
Arent 8 points and 8 boards (Seems reasonable on thirty minutes for the biggest guy on the team, especially given the fact he shot above 30% from 3 point range in Juco - meaning he has reasonable range for a big guy)
You are getting 46 points and 24 boards from you 3, 4 and 5 position. That works and you should not have major foul trouble issues. If you do have foul trouble you have Washington, Neal and Honore to come off the bench.