If you have access to a large Home Center type store, they sell flexible rope lighting very inexpensively. It can be cut to length. Just pull the end cap off, cut it where you want and put the cap back in. Needless to say, cut it when it's not plugged in.
Makes a great tank inspection light.
As far as rust in a steel tank after rinsing, most call it "Rust Bloom" and claim it is not harmful to the tank or person breathing it.
I prefer to not have it and there are two ways to deal with it. One, blow Nitrogen into the tank as soon as you finish a hot water rinse and it won't rust as you need O2 to form rust, or I suppose you could use a clean Tank whip to remove the bloom. Then use an open ended low pressure hose to blow out all the dust.
Richie