definitely rent a boat, the shore fishing options at the park are somewhat limited to a small bay that sees a lot of lures by campers.
As far as the fishing goes...its as good as anywhere on the planet for bass especially once it opens (i hope you arrive on the 22nd or later?)
Walleye fishing is basically always tough unless its the shoulder seasons so you will have a lot more fun fishing bass and catching incidental pike.
Whatever you do, if you rent a boat, either bring a good chartplotter along, or venture out very very slow. Sturgeon bay only recently got charted in the newest navionics update. It 100% has all of the fantastic lower end removing surprises that Georgian Bay is known for. (I still have no idea how the local outfitters can afford to rent out boats in PAB)The water is also tea stained until you get out through brignal banks to the main lake making it literally impossible to see the shoals while driving with the outboard. Take it extremely slow and do your best to follow local boaters to find your way.