Here is a work around to automate OCSP stapling on Opnsense with HAproxy plugin.
Hope it helps :)
I created a script based on acme.sh's haproxy deploy hook.
As /tmp
is emptied on reboot you need to regenerate ocsp files on startup so I put the script as a startup script: /usr/local/etc/rc.syshook.d/start/99-ocsp
(symoblic links in rc.syshook.d don't work).
#!/bin/sh