Another option for you would be a large strobe on the anchor line about 6 feet or so above the anchor. You should be able to see the strobe even in very low viz for some distance. It may not be perfect, but it will help for those times when you know you are close, but just can't find the line.

Another option again is to inflate a lift bag or surface marker with a line connected to it, you can use that line to go up but you will drift.