Thank you. That wasn’t quite the right location, but editing these two files seemed to do the trick. I hope this helps someone else, and I hope VC makes this possible in a future version.
/wp-content/plugins/js_composer/include/classes/shortcodes/vc-basic-grid.php
comment out line 351 (this no longer forces custom queries to show all)
/wp-content/plugins/js_composer/config/grids/class-vc-grids-common.php
comment out lines 204 and 205 (this allows display style as an option)