Wilderness Permits When Soloing?

Headed on a last minute trip to the Sierra to do some soloing.

Much of the stuff I'm going to be doing will be in / out in the same day, but given that some of the objectives are longer we might be talking very full days (i.e. 30 hour type things).

I'm not planning on camping, though I might bring a very lightweight back in case I absolutely have to bivi. No stove.

For this type of thing do I still need a wilderness permit?

Sounds like a gray area, but I think your most accurate answer would come from the Forest Service or NPS, depending on where your trailhead is. Give 'em a call.

Edit: If you think there's a chance you could end up bivying on the route, you should get a permit. If the permits are unavailable for that day, pick a shorter route where there's almost no chance you'll get benighted. Good that you're asking because I suspect some people would just ignore the permit requirements. Have fun.