Thanks for all the tips, everyone. We just got back from our 3 day fishing trip to Lake Powell with our fishing daughter. In summary, we are now HUGE fans of night fishing. In fact, that is all that we ended up doing on the trip - fishing until 3:00 am and sleeping in until noon the next day.
As mentioned before, we didn't have time to buy a fishing light that was as powerful as we wanted (10,000 lumens), so we made our own using items all found at Home Depot, plus a waterproof set of 300 LED strip lights of green 5630 LEDs (the bright kind) ordered from Amazon. Gotta love Prime 2 day shipping! Total cost was around $30 for everything.
We wound the LED strip lights around 1" PVC and slid the unit into a clear plastic tube used for protecting fluorescent lamps. This clear plastic tube fits perfectly into 1 1/4" PVC end caps. We bought 25 feet of rubberized wire, drilled a hole in one of the end caps, threaded the wire through, tied a knot to keep it from pulling out and soldered the wires to the LED strip lights. Then we sealed it all up with Silicon Sealant.
In the bottom photo, it looks like we turned off the light to take the picture, but the ambient lighting is the same. The camera had to compensate for the brightness of the fishing light. It was pretty bright.
The first night we tried at the Wahweap marina store because they have both lights above the shop shining into the water and blue lights under the docks. If I recall correctly, the depth was about 35 feet. We lowered the green light into the water and tried our luck fishing with frozen anchovies. It was a bust. Only one fish caught in 2 hours and the line got wrapped around the underwater dock cables when we tried to pull it in. No good.
We then went to the Stateline marina store and once again lowered the light into the water. The water depth there is about 25 feet. About 10 minutes later we started to see small dots buzzing around the light. Then we started catching fish! We pulled in a number of strippers and kept only the largest 8.
The next night we went back to the Stateline marina, but went to deeper water this time. We tied up to the end of the houseboat pier across to the West from the fuel dock. The depth was about 55 feet. Once again we lowered the light and soon the small dots were buzzing around again. This time, the action was terrific. Just about every cast ended up in catching a stripper - or losing the anchovy to a sneaky fish. The fish were indeed sneaky and subtle. We used braided line to feel the small tugs and had to set the hook at just the right time or the anchovy was gone. We ended up catching 31 fish that night. For the first time, we have a photo like the ones that you guys post here all the time with a huge pile of fish!
The final night we went even further back into the houseboat storage area in about 65 feet of water. The fishing was a bit slower, but the fish that we caught were bigger. We also saw a bunch of small fish circling around the light which we hadn't seen at the other locations. Not sure what kind of fish they were. It was fun to watch them swim around the light - and then all-of-a-sudden disappear when a large stripper swam by. They came back a few minutes later. We ended up with 14 fish for the night.
Thanks again for all the help and advice from Wayne and others. It was a great trip.