I"m glad to see the personnel compartments being put behind the cab. It's a great idea that I never thought of but wished I had.
The first fire truck I modified for holding someone to handle a fire hose while the vehicle was in motion was in the middle seventies in Perris California. One of the fireman had been run over while running beside the truck on a grass fire, not a fatal, just legs injured. The chief brought me a pumper and I made an extended bumper where the fireman could stand in front of the truck and be safety belted in and also in full view of the driver.
Then in the nineties here in Texas our fire department got two pumpers for grass fires. I made a rear cage that could have two fireman manning hoses while the truck was in motion.
The problem with both my ideas is the fireman is in greater danger being out front or behind the main part of the vehicle. The mid-mount concept is much smarter.