As a paramedic that has experienced anaphylaxis personally, I would not hesitate to give someone with BP of 60 systolic epi. According to my allergy specialist people wait to long to give epi and it is hard to reverse the "flushed toilet" quickly. I hated the after effects of epi and so when I had the second "idiopathic" anaphylactic event, I convinced my crew to go straight to benedryl and fluids. (I did not initially present with hives- just itchy hands and feet to very low BP then unconsciousness). He had a stern discussion regarding that decision after the fact. He reminded me of EPIs role in helping to super charge the compensatory system and he strongly encouraged its use early, if there was any suspicion anayphylaxis was the cause. I also believe a recognizable medical alert tag is important. But I have noticed that my basic instructors are not emphasizing the need for a quick search for jewelry. All it needs is a contact number if there are mulitiple allergens.
Just my thoughts on the matter...