Gotta tell ya Steve J. Go to a BPS and get your hands on a demo HDS and take a look at the maps on it for the Lake Insight. You could scroll over to Okitibbee and see what it will display. I looked at one and it's head and shoulders over anything I've seen before. Lowrance lists Okitibbee as being covered too.

The catch is Lowrance's reputation for customer service and the price is on up there compared to the alternatives though.

Lake Insight - Detailed Lake | LOWRANCE

Wannabe...