Why not? That's exactly what I do. Watts and cadence are watts and cadence.

As for mental, I got a power meter. I don't look at speed, it's just a nice number at the end of a ride which I like to look at. You'll be happy knowing you're putting your wattage out, and the speed means nothing.

BTW, when i have interval days sometimes I specifically save them for the headwind portion of my route. Otherwise I'd be zipping along at 30mph for a few minutes at a time and I end up covering too much ground. I'll inevitably I'll have a stop sign or crosswalk or something come up.