Thats funny my dojo is in a room inside a baseball complex. An I agree on seeing some of the same reaction of parents and I get some strange looks when I come out of our dojo to use the restroom (to be sick) soaking wet in sweat.
I know how you feel, but I would not quit the Martial Arts over it. I recently felt like doing that to, but before I would quit I would went some where else.
They are your believes and should be respected. Me personly I would not show him especially since he left the dojo on not so good terms and out respect for the dojo.
I usually break down the kata that I'm going to do at the tourny in to parts. for sparring off the line techniques. A lot of Combinations. We also do alot of conditioning, too.