I'm glad we found it (my wife was organizing her new craft space and found it in some things-- we still have no clue how it got there!). I will submit it to the Combat Art Collection of the National Museum of the Marine Corps in Quantico, where it belongs.
Sketches like this one are very valuable, I think, because though they may lack refinement or be a bit "off," they are one of a kind records of something the artist saw.
This sketch and the photos I took were used as inspiration and reference for a portrait sketch I did later of the same subject: