I'd suffer and lose weight like crazy at 3500 calories per day on most of my tours. Maybe it would be OK for 50 mile days where it is flat, but I would have never made it on that in the Sierras (averaged 50 mile days, but massive amounts of climbing), on the Santa Fe Trail (averaged 80 mile days), or on the TA (averaged 60 mile days). I was at about 5000 calories per day on those three tours and lost weight.

That said the DelMarVa peninsula is dead flat, so if the headwinds aren't too bad, caloric requirements may be less.