The above illustration is by Steve Fastner and Rich Larson, perhaps better known simply as Fastner and Larson. A gent known as Gordon appears to be the first one to let me know about this back in 2005. Someone finally sent a scan of it in 2006. And I've just sat on it since. Sorry! I've been told this art was included in one of the pair's books, but I don't know which one. If you do, please leave a comment or drop me a a line.
It also turns out that in the years since I was first told about it, Fastner and Larson have uploaded it to their own site. I must warn you that much of the art on their site is not safe for work (NSFW), as it features scantily clad and less ladies. But you can buy a $10 print (plus $5 shipping) or the $400 original Rom illustration -- an 8½ x 11" work in marker and airbrush -- there. Most intriguing, however, is that the site says this Rom illustration is "the study for a larger private commission." I wonder what that looks like?