The answer is simple.
Hardest for scratch from back tees - find the course with the highest course rating from those tees.
Hardest course for bogey from regular tees - find the course with highest bogey rating from those tees.
Now how to find those, I don't know. But I bet an astute internet searcher with a few minutes on his hands could find this.
TH
Here's a vote for one of Tom's favorite courses as hardest for 18 hdcp, The Ranch near San Jose, Ca., target golf with huge changes in elevation and lost ball penalties for every bad shot.
I also would nominate Ko'olau in Hawaii as hardest I have played. Visually intimidating and lost ball penalties for every bad shot.
For low handicaps, the Stadium Course at PGA West from the back tees. Just look at the Q School scores on that course.
Also Industry Hills in Los Angeles from the back tees is brutal even for low hndcps.
With the wind up, which is the case most often, Wente golf course near Livermore, Ca is brutal and had the highest scores on the Nationwide Tour a few years ago.