These are the lights I use.  My philosophy was, if I put the lights on the bottom it would scare them up to the top where I could see them.  Well, I've never got my full 5 gal. limit, but I've had a few good outings.

The light consists of a car headlight, PVC frame, cement sprinkler protectors, a 15' extension cord and some heavy tie wraps (to hold the bulb, weights, and wires to the frame).

One thing you have to be aware of is that while the headlights are called "sealed beam" they do leak at the connectors.  Also, if the connectors are exposed to salt water they will corrode through after your first time out.  Before I make my electrical connections I glue a paper cup form around the connectors.  After I connect the wires I fill the cup with some kind of RTV type sealer.  This is the clear rubbery kind from any hardware store.  You may wish to apply this a little at a time so it will cure properly.  You can't use too much when it comes to protecting your connections and/or sealing the lights.

For the frames I use 1/2" CPVC.  CPVC has thicker walls and will stand up to more abuse than regular PVC.

The frame also makes a handy place to wrap the cords to keep things neat.  Since I only have a 16' bass boat, space is at a premium.  With 2 people, 4 lights, 2 batteries, 2 anchors, cooler, 5gal bucket, and a partridge in a pear tree... There is no room for any dancing!

The frame also makes a great handle for tossing the lights far out into the oncoming tide.  Sometimes the lights don't land right side up.  Since the bulb is a big air bubble, all you have to do is give a little tug on the cord and they will right themselves.

Remember to secure the extension cords to the frame.  Since this what you will be using to retrieve them when you are done.

As for power for my lights I use 12v gel cells from The Battery Shop on Edgewater just south of Lee Rd. 407-292-7480.  When he has them in stock they are around $50 each, but they are worth it.  One of these batteries will run two of these lights for over 4 hours!  Since I have 4 lights I use two batteries.  Careful handling them since they weigh about 85# each.