The fairings really do help to get more top end speed, I have used various fairings on my moroized bikes to help cut down on high speed drag too. They especially help when you crouch with a full face helmet into the front fairing and your helmet becomes an extension of the fairing and your back becomes teardrop shaped to the bike. Thanks for sharing your awesome recumbents Lowracer, I bet they all went very fast and slipped through the air with minimal effort. I especially like this trike you made, bet it was a blast!
Here are the bikes I've done with windscreens which are noticeably effective in a crouch according to the speedometer.
The Cag powered moped
and the KTM Chopper
A simple windscreen is pretty easy to make from polycarbonate and a heat gun, or various front fairings can be bought online for cheap, they're well worth it if you're looking to smooth out the cruising experience because they make a bubble of calm air behind them, and work great for top speed if you crouch behind them.