You can stay at the Valley and Upper Pines and other campgrounds are not as crowded but no hook ups.
We winter camped at 28F and in heavy snow with no problems on our Coleman Lite without heated pipes or tank.
Yes, be prepared to drive through icy roads or even be stranded inside the park when the close the roads due to heavy snowfall.
And too for driving over icy road. My 4x4 tow vehicle helped but had to crawl as some hairpin curves.
But Yosemite is absolutely beautiful and breath taking in winter and bucket list worthy.