If there is enough snow, bypass the ledges on the left side of the canyon. Otherwise, follow the trail up the ledges to LBSL.
Study the route, especially from UBSL to Iceberg Lake. It’s easy to get confused if you haven’t been there before.
There are several ways up the chute. Just pick whatever looks good, depending on the amount and firmness of the snow.
The final 400 will be your biggest challenge. When it’s dry, it’s enjoyable class 3 rock. In April, it will probably have a lot of snow and some true ice, making it much harder. You will probably have to climb it wearing crampons. Most people do it un-roped, but the guide services use ropes.
Day-hiking the MR in winter conditions requires a lot of determination and stamina, enough technical skills to motor up and down without hesitating, avoiding any route-finding mistakes, good snow conditions, and good weather. Very few people successfully day-hike the MR in April as their first attempt on Whitney.
I suggest spending a night at Iceberg Lake or 1-2 nights at UBSL. Plan on camping in the snow. A three-season tent is probably OK, but I always build snow walls. A 20º bag definitely wouldn’t keep me warm. I used a 0º bag and a 3-season tent at Iceberg Lake when I did Whitney, Muir, and Russell in April 2009.
