@Squawk7700 - my understanding is that the PAC 750 parachute drop plane operates under IFR so it would be under control of ATC and that ATC would use radar to maintain separation from other traffic, including the canopies.
Your map is spot on. I fly out west often on weekends and will track from the BOM tower to Brighton to get back to YMMB. Brighton is a few nm south of the Elwood drop zone.
Training traffic going from YMMB via Albert Park Lake to YMEN might be a problem, but would more likely be inland of the drop zone.
I've met some of the skydive people who operate the PAC 750 over Elwood and get the impression they are more professional and well resourced than your typical weekend country skydive club. At least their pilots get paid properly.