I do 3 trainees all the time.
The key is to prioritise the trainees. The 2 most important trainees get the first two games of the week, if they don't get their 48 due to foul out, bad coach substitutions or injuries, you play them in the 3rd game to make up the minutes. The 3rd guy gets the full 48 only if the first two do, and if he doesn't get the full 48 minutes, that's ok.
So making the two best trainees a priority is the way to go, and the 3rd guy is along for the ride (assuming there's room).