Here are a few pictures of what can be done. The first one is a speed plane at the German Speed Cup. The second one was built by one of my customers and there is some discussion of how in this thread.
http://www.rcuniverse.com/forum/m_6034143/tm.htm
It is a long thread and it is in the second half.
The third one is one I built for a kit I sell. It is made of contest balsa and then glassed with .75 cloth.
I have a chapter in PDF format on model airplane cowl design and building written by a well know person. PM if you are interested in a link.