How about a beacon and windsock on the ambulance and/or firetruck?
The beacon would make things easier locating the scene. The windsock is a very low tech, low cost piece of kit that gives the pilot useful information. Of course, you run into the risk of requiring this once you start using it.
My experience is that there is nothing to be gained from someone else doing recces for you. I talk to those on scene if I have a chance, most people have the sense to clear a large enough area, but many find it hard to look past the landing area and into the approach.
KISS is the best consideration. (Keep It Simple)