We use a wand and a desk lamp turned sideways just behind the bottle being filled, you should be able to easily see through it that way. Trying to light from the bottom is actually harder to see since the beer makes the bottle even more opaque than it is to start out.
Also, thumbs up for the dishwasher door, that's what we bottle onto. We clean the bottles as their emptied and then store them. Run them through the dishwasher upside down on high heat with no soap immediately before bottling. Bottling bucket sits on the counter, and we fill bottles right onto the open door with the desk lamp behind the bottle. easy to see so you don't spill much but if you do dribble a little it is drained right through the dishwasher and cleaned next time it's run. We've never had a bottle infection this way either.