I've done 3 days 2 nights in early April at around 250. It's long days but was fun. You'll have no problem with 4 days. I seriously doubt early may will be that low this year as long as it warms at all. Average for May 1 is around 360. It's just dropped recently due to getting cold again, it'll come back up, there is a butt load of snow just waiting for it's sprint to the sea.
"If you dont do it this year, you will be one year older when you do"