Looks like a great idea and a cool project! Be sure to post pics as you go along.

A few things to consider for an 8-foot model boat:

One or two cordless drill motors may not provide enough power. They are often high-RPM motors that would need to use some sort of gear reduction unit to avoid burning them up. Your drawing looks to be a direct drive, so if you want to go as cheap as possible, look for high torque, lower RPM motors that you can directly turn the propeller(s) with. Check the "All Electronics" company website. They usually have a lot of cheap DC motor types and sizes to choose from. The $15 electric scooter motor looks interesting .

I've seen a few huge r/c boats out there running with old trolling motors, eliminating the need to buy a propeller, stuffing tube, drive shaft, etc.

It's going to need a lot of weight strategically placed to get the hull to sit in the water correctly and not be blown around by wind. Large sealed gel cell batteries are good for weight. Plus you'll have pleanty of amps to feed the motors. At 8-feet, you could also put a deep-cycle marine battery in there, but keep in mind some require maintenance and can leak fluids and fumes.

Water pickups require speed. Not sure this boat will go fast enough for a water pickup to work without some kind of pump. But if you can find the right motor(s), you won't need auxillary water cooling anyway.

Just by it's shape alone, a long and lean boat like this may be hard to steer with just a single rudder behind the prop. Some modelers use multiple rudder setups or bow thrusters (small propellors mounted inside the front of the hull to push it right/left) to overcome this.

Most importantly have fun and don't get discoraged if everything doesn't come together on the first try.