To follow up on the ballast install, I went ahead and added a T and another fitting to the vent of the 720’s.
Everything worked great but they didn’t seem to drain as well as expected. One of the check valves didn’t seem to be working, when I put my hand over the thru hull it finally started to suck the rest of the water from the 720 through the rear bag and into the pump. I’ll have to make sure I didn’t install it backwards. Part of the issue could be an excessive amount of air in the system since it was the first time out.
I also realized the stock front bag has 2 vents/thru hulls so I need a second check valve up there.