I processed Cibachrome (predessesor of Ilfochrome) in trays at 20c years ago and it worked fine, I just did a test to determine the correct development time. I also used two bath black and white developers to help control the high contrast and ordinary fixer, the only ciba chemistry that I used was the bleach and this greatly reduced the chemical costs. The prints are as good today as when they were made in 1988.