That's the same tank I have, and I use this light from Amazon https://www.amazon.com/gp/product/B09BF49N3N

I got it in January. I've dropped it in the water twice and it still works.

When I wiggle the cord, the light will get brighter and dimmer and that's why I don't think it's fantastic quality. Yet I haven't rushed out to replace it.

Same brand has one that has more LEDs on it, and I think you might like that one slightly better. Though I still suspect it isn't great quality.

https://www.amazon.com/GLOGLOW-Aquarium-Underwater-Indoor-Plants/dp/B09JKW9R4S/

I'm very interested in how you'll modify it to accommodate cords. I've been thinking about how to do that too. :)