For weather protection on a commuter bike I use a Coroplast fairing. A tailbox is necessary to get the airflow back together behind the rider.
This is cut from a 2' x 4' piece of 4mm Coroplast.
This was an old design that gave modest improvements and was stable in cross winds. A good design will cover from the shoulders to just below the knees. Get the riding position comfortable then build a shell around yourself. Try the HPV Shell software at recumbents.com for either a 3:1 aspect or a 5:1 aspect with a 75% Kamm cut off. Make sure you can get on and off the saddle easily.