I have used a sled in Yosemite on relatively flat ground and also on hilly terrain on a different trip. First of all, it depends on the sled. Mine was a kid's sled and not that well suited for hauling gear because of the rounded bottom, as I learned the hard way. I used PVC poles clipped to it and the waistband on my pack. That worked really well. A better sled is the Paris Expedition or similar sled with a flat bottom. The Paris sleds are orange. You can buy all the hardware ready made or make it yourself from stuff you'd find at Home Depot, which is way cheaper.

I used my sled with snowshoes and skis and for me, in spite of the problems, it enabled me to camp alone with full winter gear and an expedition tent and not try to carry a really heavy pack, which I can't do. well worth trying.

A good source of info is www.wintertrekking.com The members of that site make toboggans, pulks and sleds of all kinds. Lots of posts on them.
Here is a site that sells sled gear - www.skipulk.com