This is typical for many bass boats. If you search the forum you'll see where a lot of the guys had to cut this joint free. Since you have the cracks already there you should be able to get the sawsall blade down into the cavity to make the cut. I think you'll find that the resin joint could be quite extensive and could require the blade length of the sawsall to get it cut free.Where the outboard was is the only place that doesn't have a seam where the two pieces were conjoined.
It's trying to take off GM! Do you agree with woodon and where that tape is, is a good place to cut?