I don't have any knowledge of GPS programmable perimeters. I think you're kidding with what the post above infers but for others, if not you, I want to encourage to have reasonable, and humane, expectations about training, effectiveness, and how it's supposed to work.
There are two categories of eCollar- I use both. They are both good training aids but have slightly different purposes. However, the goal in both is to not have to zap.
1) Active monitoring (you have the remote and utilize the collar to reinforce verbal commands). This is like an invisible leash. It took about two weeks until the vibrate-only feature and command were enough, and another month until the command itself was reliable.
2) Passive Monitoring (you set a perimeter that the dog learns- though training not pain- not to cross). This is your invisible fence, and what you appear to be asking about. It took two weeks of consistent daily training for each of my dogs on our electric fence (buried line). Assuming you have the ability to physically flag the boundaries at the lake and work daily on it up to Memorial, I don't think the GPS version would be any different.
Please don't just set a parameter and leave it to the ZAP to tell them they've gone too far. It will only terrorize and confuse your dog.