Another vote for trainer. If you really want to stick to your program's stricter parameters, they're the way to go IMO.
I have a few longer hills and a few flat stretches in my region that I use for the looser workouts and for recovery rides, but when it comes to the workouts with narrow parameters...

And I don't think it's miserable at all. It's a lot less miserable than working your butt off, holding your perfect/fluid form through a sweet, sweet burn... and then having to stop because of some stupid red light.