The City of Ft. Lauderdale has a firefighter who is a "little person". Don't know him personally but I saw him at the academy years ago. It's been some years now and I've heard he's a Driver Engineer now.
I do not see any problem with height in the fire service so long as the butt of your SCBA is not impeding movement as you are performing fire fighting operations. Good luck!!
To have height standards could be judged as discriminatory by some so I would suspect that no department would ever put themselves in a position to exclude someone because they are not tall. The bottom line here is that the individual, regardless of size, has to successfully pass a physical agility related course / activity to demonstrate their ability to do the job using tools that are commonly found on a fire responding fire engine.
The testing process dependant upon the department you are seeking, may include a 24' extension ladder evolution. For which a firefighter has to remove the ladder from it's holder, carry and replace. Height may play a role, then again depending on upper body strength, it may not. I have seen some shorter firefighters complete the evolution... Extra points would be given for your excellent smile :)
Im a terribly short dude. I HATE LADDER WORK! Even if I am pulling a line off another companies bed I can have trouble because if it's like Sutphen or LTD, those bastards are really tall for me. I can struggle a little trying to pull a rear mounted line.