Here's an insightful piece from the 'bent perspective from a guy who did PBP on a Lightning, talking about the false perception of being "too low" on a 'bent...
 
(whole article:  http://www.randonneurs.bc.ca/newsletter/submissions_2006/004_pbp-and-recumbents. html )
 
 
Will You Be Seen?
 
 
Some people who have not ridden a recumbent somehow have the idea that a recumbent is so low that there is just no way a motorist will ever see it. The height of absurdity experienced by recumbent riders is the inevitable motorist who stops beside them on their bike, looks up from their sports car and says: "aren’t you afraid of being so low?" The plain fact is that most car seats are lower than most recumbent bicycle seats, but recumbent cyclists don’t stop beside cars and say "aren’t you afraid of being so low?" Equally stunning logic could be posed to the lines painted on the road, which should therefore be invisible.
 
On an upright bicycle the cyclist towers above car roofs in what seems like a circus act after riding a recumbent. A recumbent cyclist is in the same position as a motorist and the sight lines and visibility available to a recumbent cyclist are the same as a car. Anyone who has driven a car will be familiar with the recumbent cycling position. The real problem arises when switching from a recumbent to an upright bike which can make the cyclist ask themselves "am I too high?"
 
If anything, recumbents are one of the most visible vehicles on the road because they are unusual and motorists tend to notice unusual and interesting objects.