Practice, Practice, Practice. You are talking roughly 20 miles per day in some roller coaster stuff with varying grades and elevation change. Stair Climber in the gym with pack every day would be good, unless you are already tuned up to that level. March weather can be good or bad - meaning too hot and/or snow and ice. With the weather patterns the last few years, anything goes.
Suggestions: get your pack weight down; plan on re-supply of food at Neels Gap to save weight for first 2 days; enjoy yourself despite the pain!!!!
Would like to be back on the trail but am back in an old job to help fill in for folks who retired. Maybe next year!
Professional Prevaricator: Part-time dealer in Yarns, Tales, Half-Truths, & Outright Lies -1st half-hour session at no cost (Lawyers and Doctors excepted).