re: What's the purpose of this boat?

The term we use is "Tower Boat". Lots of the guys I compete with and against (redfish tourney) use them for scouting. They are incredibly affective for what they do.
If you look closely at the hull from the back you can see it's a tunnel hull, that tunnel runs the length of the boat and narrows from front to back and funnels water to the motor. The hull design enables the boat to run in less water than it floats in (typically 6” water). With it being able to stay on pad at 10-15 mph (depending on the hull manufacturer) you can cover pond after pond until you find the fish you are looking for. Look closely at the fact the bottom of the hull is below the prop.

The controls at the top gives you a bird’s eye view of the fish as you are “burning” banks and there is never a need to stop unless you find the fish you are looking for. In most cases you can simply mark GPS spots where fish are as you are “burning” and come back later in the day and hit the best spots.

They are so good at scouting there have been times where some tournament trails forbid their use and those that don't have them HATE them...

I know who owns this particular rig... Glad to know where he's scouting