Here's a possible resolution to two mutually exclusive taboos:
1. Males may not work in medicine.
2. Females may not be in the military.
So what answer is there for military medics?
The same answer I seem to have for pretty much everything: Mechs!
Medics on the front lines are actually mechs operated remotely by healers. That way, they're not technically in combat. Healers are already experts at piloting mechs remotely since they use micro mechs for non invasive internal surgery.
Another option is that battlefield medics are a regular position. The people who seek to become medics are all either males who want to learn medicine or females who want to see combat, but the taboos against male healers and female soldiers are so strong that the healers are reluctant to teach the males much medicine and the soldiers are reluctant to teach the females much about combat, so you have either a decent soldier whose bad at medicine, or an excellent doctor who isn't good in a fight.
Of the two possible solutions, I have to admit the second option opens up more worldbuilding opportunities, but I just can't say no to mechs.