In my opinion:
Leave the 45 minute halves, but give set times for the ball to returned into play, say 15 seconds for a throw in, 20 seconds for a goal kick, with a countdown timer on the big screen. Throw goes the other way if you don't complete in time, or a corner given if the goal kick isn't taken.
Treat injuries on the pitch, let the game go on, unless it gets too near the "injured" person, or its in front of the goal.
Stop the clock after a goal, restart it from the kick off.
4 substitutes
A sin bin for the first yellow, reduce the number of "professional" fouls.
Nothing else is needed.