As anyone who plays or teaches bass clarinet knows well, altissimo fingerings for bass clarinet can be quite confusing. The standard B-flat fingerings work sometimes, but not in all situations. Some fingerings may even work on one bass but not speak at all on another.
This page from the website of Terje Lerstad is a great resource for anyone dealing with these issues. Lerstad has posted an article he and Thomas Aber wrote for The Clarinet entitled "Altissimo Register Fingerings for the Bass Clarinet," as well as an article by Lerstad about altissimo fingerings for contrabass and contra-alto clarinet. Both of these articles are accompanied by fingering charts.
One issue that the articles explain well is the difference between the double and single register vent systems, and their effect on altissimo fingerings for the low clarinets. Because student horns often have only a single register vent, certain categories of fingerings will not work as well for them. Other fingerings work great for single-vent horns, but not double. The charts differentiate these by adding an "S" under fingerings that work for double-vent horns (most Selmer and Buffet basses) and an "L" under those that work for single-vent horns (older Leblancs and others). These articles and fingering charts would be worthwhile for any bass clarinet player or teacher to explore.