ok, here is a bad pic of an exposed engine w z-top in a poorly lit garage through some darkened glass ...
for a split second a few years ago i thought about going to a clear cover, but either lots of $$$ of gotta fabticate your own. and, as others have noted, it would get crudded-up with all kinds of unfortunate debris in short order. not to mention the need to incessently clean the engine.