A little secret - I want to say Tuner had Dick Ott's engines running around 28* for road racing at Laguna and Portland. I was quite surprise when Dick mentioned that, and pretty sure Mike Ritz (Team Starfish) said something similar - engine also built by Ott. You're at different elevation and obviously different engine - I don't know what secret sauce went into theirs but apparently they did not need or want a lot of spark lead in the conditions they were running. Probably built to be very efficient in the rpm range needed for vintage racing.
My understanding is the coolant temps should not climb too much on the road course. The speeds help get rid of the heat. The oil temperature is more often the issue. As long as it stabilizes at some point then probably can get away without a cooler by choosing an appropriate grade oil to account for the higher temperature. That's been my plan since track events are secondary. My one road course event with the '67 didn't really get the oil too hot. But that was dip your toes type event. Even there I was ready. I brought heavier grade oils andran with the accusump empty. That would let me put in close two additrional quarts of heavier weight oil if needed.