2 things
first of all, haven’t we been there done that on this topic already?
second of all, i’ve met a few ppl in the med field including emt’s. emt’s who do it as a profession (ie 8 or 12 hour shifts) spend the time in a metal box with their partner. now i know hatzolah members don’t do that, the woman would be in VERY close proximity to the men if the men do the driving 1/2. just one example.
and third of all (yes i know i can’t add) if this was really a good and shayach idea wouldn’t the hatzolah boards in dif cities have already asked their rabbanim if this was appropriate etc? i feel like ppl are paskenin s/t rabbanim have already decided