Great time of year. "Unfortunately" I just got a job and have a May trip planned for the Grand.
I would recommend buying or renting a "blaster". You should see mostly warmer days that late in the winter but a blaster really helps for those colder days, not to mention how quickly it warms up water for dish cleaning.
So many great camps that time of year that would be miserable during the summer. We had so many layovers on our January trip it was ridiculous. If it works out, Granite Park is an amazing place to crash and explore in the winter.