For starters you do not have gay chinchillas. Animals do not have homosexual behaviors in the same sense people do.
this simply is not true. while i agree that most humping is related to dominance issues, a sweeping statement that animals do not have homosexual behaviours in the same sense people do is highly incorrect. gay penguins, for example, nest together (very much like humans) and even pretend stones are their eggs.
sorry but i do get wound up to no end when people claim that either gay animals do not exist or that they do not show gay behaviour. they do.
chinchi and fluffy took about two months of introductions and the first few weeks, it would be seconds before chinchi would start chasing and humping and it was all quite aggressive so quite often they'd get 5 seconds before they got separated (of course then we thought they were both boys, it later turned out that fluffy is a girl) - what helped in the end was letting them have a playtime in a different room so there was a lot of unknown stuff to explore and they both went off to do that and ran into each other every so often and it got better from then on. and once they decided they actually liked each other, they groomed faces for an hour solid.
i think you've got a good start! 30 minutes before any trouble starts is quite good
i think patience is the key.
could you maybe do, 30 minutes together, 30 minutes apart, 30 minutes together... and then reduce the apart bit?