Just curious (and, for the record, I'm not advocating slamming her with it, just taking the edge off of the OD), but why?
Once you remove the medication patches you will be reducing her pain relief as well as the rate of absorbtion now that she is not in the tub. Even without slamming it, which I don't think anyone here would do. You might have a patient in pain which you cannot control nd the effects of that. Since an opioid will last longer than narcan will, in order to keep the edge off you will need to keep readministering it or set up a drip.
All of the harmful effects of narcan studies I have seen (including pulmonary edema) were demonstrated in the elderly, not 20 year old heroin addicts.
If you can simply remove the source and ventilate the patient for the time (probably about 1/2 hour or so, which is a majority of your transport here it seems) it takes for her to come around without adding a chemical to the mix, why not just manage her airway? Her HR is a little low, but her BP is still in a reasonable range for somebody of her age.
Speaking of HR and BP, when her hert does start suddenly increasing contractility and rate you are going to stress the myocardium by acutely making it work harder. She has a hstory and management of hyperthyroid, which is going to add yet more stress to that. Similar in thinking to: you would not want to acutely reverse hyperglycemia, why would you acutely reverse this in a frail person?
Let's say you do start to get an onset or exaxerbation of pulmonary edema? Are you going to start adding furosimide to fix that?
I am not saying narcan is wrong, but in this case it could take you down a path you don't want to go. If you just support her breathing you can eliminate all of that potential. Pathology doesn't happen in a bubble, patients develop compensatory mechanisms over a long time, and if you start rapidly changing their stasis, you can not only make things worse for them, but can cause a really big headache for yourself.