Hi Corsair,
well you are daring I must say... sometimes people climb in the afterseason (march) and sometimes the are lucky. Also sometimes people climb in the preseason (sept-nov) and they might be lucky, but few people try it in the darkest, coldest and windiest months of June/July as chances of success are low and chances of accidents (frostbite, blown away) are huge.
So I would recommend against it.. it is ski season down there at 2700m, not for nothing! Imagine climbing a summit 4 kms above the skilifts in Europe or the US..
I just came back from climbing Ojos de Salado and Acon, Ojos is easer to access and quite a lot warmer, so that might be a possibility, although usually in this season climbers go farther north to Peru and Equador to climb.
Keep us posted!