So this spot technically wouldn't work for a night game, lest you risk getting a ticket or towed for not being a resident (not sure how they'd know).
However for a day game, you can park here for free, walk to the Levee and wait for the Southbank Shuttle which runs every 15 minutes and only costs $1. We did this and found it very simple, safe, and cheap!
For my full guide to saving money at Great American Ballpark, click here.