If the fluid really is boiling, I would add a fluid cooler. Safety first and extend the life of the system components. Many vehicles have OEM coolers. I think I have one of the OEM coolers for this application ( hangs at the p/s fluid pump ) laying around here somewhere. Came from a 75 Valiant Brougham, slant 6 with towing package.
GM placed a neat little cooler under some FWD vehicles, Grand Prix, Grand AM for examples. Its at the bottom of the firewall at right side, under the car. It faces the road in those applications but could be mounted most anywhere. My imagination suggests under the battery tray for this application.
