I thought both Philip and M.H. made good points, especially about having a MOB kill switch.

After looking on the map I see that this lake is pretty narrow so even if you went overboard you stand a good chance of swimming to shore, especially in your life vest.

I am not sure how large your boat really is. Some 15 footers are heavy enough that you could climb in over the gunwale without tipping, but if it is a light boat you might be dragging the gunwale down to the water and almost swimming into the boat.

I would consider a rope or slat ladder on a light boat.
I would also consider making sure it could be reached from the water at all times, possibly lashed with light line over the gunwale or stern.

Another idea might be a small step on the stern to pull yourself up on.