Maps of Vietnam which include locations for US firebases, air force and naval bases, medical bases, and other major military locations do exist. They are most readily found through the Websites of individual military units which served during the Vietnam War.
Maps of US military installations in Vietnam may be found through the Websites of former military personnel who have maintained the integrity of their units since the end of the war through keeping in touch, holding reunions, and so forth. One such highly-ranked Website, http://www.landscaper.net/maproom.htm, is maintained by former personnel of the 15th Field Artillery. Some former military personnel have also taken it upon themselves to create a record of US bases using Google maps, most of which are listed as works in progress.