I've been fiddling with an idea to mandate two hour games. The nature of baseball is that one team can stall, no matter how much the umpires try to avoid that.
How about giving teams 60 minutes on offense, then cutting them off? On offense they might as well play as quickly as possible.
What about on defense? A team would always have the incentive to delay and run out the the other team's offensive clock. How about time delayed on defense being subtracted from their 60 minutes of offensive time.
It might actually work. How about trying it in the Experimental League that I recommended?