I pretty much just do base on the trainer, and MAP testing.
I do all my intervals on the road. Often hilly and windy. Even with stop signs on some courses. It's a good skill to learn to maintain power in these conditions. Not that you want to race with constant power, but just to train your brain and legs to work together so you can be intentional when you like. For descending tailwinds, I'll brake if necessary. For stop signs, I'll brake and keep pedaling, maintaining power, and almost stopping -- sometimes I'll come out the other side with a slight power gain.