It seems passing options to ASTAP via the "Options:" text box under Ekos' Align tab are ignored if edited. The only options supported are the ones defined in the Ekos configuration GUI when you press the little edit button. I would suggest that this text box become disabled or let the user override it after a warning.
I was able to overcome the limitation by creating a bash script:
/opt/astap/astap -r 90 -fov 1.62 "$@"
I then poined Ekos to this script after giving it execution permissions (chmod +x script.sh).