your plate chiller will bring your beer down from 205 to 85 degrees in seconds
you can pitch at that temp if your starter is at room temp, and then bring down your wort to whatever you want to ferment at, I used to do that at darwins all the time, pitch at like 80-85 ferment at 67-70, because i ran into the same problems that you did with ground water as my only cooling
you should always pitch as fast as possible
i have pitched some yeast strains as high as 90 degrees before, and then brought them down to room temp, or I have just let them ferment out
i do brett pitches anywhere from 62 to 85 degrees with my yeast always being at room temp
you can pitch at that temp if your starter is at room temp, and then bring down your wort to whatever you want to ferment at, I used to do that at darwins all the time, pitch at like 80-85 ferment at 67-70, because i ran into the same problems that you did with ground water as my only cooling
you should always pitch as fast as possible
i have pitched some yeast strains as high as 90 degrees before, and then brought them down to room temp, or I have just let them ferment out
i do brett pitches anywhere from 62 to 85 degrees with my yeast always being at room temp