"Lightfootcycles" have a few practical designs they sell, and the company is in Montana. However you can make your own if you are resaursfull and have friends in the right places.
We made ours for a chrome tank covers that were 6 feet long and had to open 6 times a day, lasted for years. They are esentially made from light pipes bent the way you like with sewn rip-stop nylon cloth. Ours worked excelent for 12 years, good luck.
Ebike in use:
LWB Recumbent bike, Sram i-9 internal gears.
Power supply: 58V, 16 amp/hr, lipo batteries.
max speed: 50 km/h (30 mph),
max range: 40 km's, incl stop&go few times, minimal pedaling.