Good way to extract Coupon fields from Notification Email

Hi, I would like to be able to exclude Coupon information from Product Summary Table that gets appended to the Customer Notification email. I am using a {all_fields} merge tag. I have spent hours trying to figure this out, obviously the initial attempt was with gform_merge_tag_filter, although a field with type of coupon exists, excluding it does not affect the Product Summary.
As a meantime solution I store the value of Coupon field in a variable, and later hook into gform_pre_send_email and do a string replace on <ul style="margin:0"><li style="padding:4px 0 4px 0">Coupon Code: '.$coupon_field.'</li></ul>.
While this works just fine, it’s not the best solution IMHO.
For example, what if instead of removing just the coupon code, I needed to remove the whole table row? I think doing a string replace on a whole row just seems a bit excessive. Or what if I simply wanted that row to be 1st on the Prod. summary.
Would really appreciate your input on this, is there really no way to clear the Coupon field data before it gets passed to notification, or did I miss something while digging through the filters?
Thanks in advance for your help.