For what it's worth, my take on stereotype is this.
All the best comedy characters are stereotypes. Meldrew, Del Boy, Brent etc. But the stereotype is just the skeleton you hang the comedy 'meat' off. It's all about layers. If a gay character is just there because he's a funny camp gay without depth or layers (and I'm not saying yours is) then that's just lazy stereotyping, especially if its a main character. You can get away with it (slightly) more if it's just someone that occasionally pops up in a script.
I don't really agree that it's a fine line to tread - the distinction between bad and good stereotyping is very clear. Good stereotypes have layers and inner conflicts and a very real sense of their own being, just liuke real people do.
For instance if you have an Indian character, does he eat curry and drive a taxi for a living? Maybe. But if you leave it there it's just lazy and insulting. Whereas if he eats curry and drives a taxi but harbours a secret desire to become a stand-up comedian like his idol Bernard Manning, and he constantly tries out his act on his horrified captive taxi audience, then you've still got a stereotype but a stereotype that's being subverted, and that's infinitely more interesting than him being there for no other reason than to shake his head from side-to-side and say "Goodness gracious me." 
