I am taking a similar drug called Soriatane for psoriasis. It makes my lips very dry and chapped - I've been taking the drug for close to 2 months and that particular side effect is not going away. I play trombone, but I'm not in a situation where I have to play everyday which is good because my lower lip is in pretty bad shape. I don't think I could do drum corps with my lips this bad.
Additionally, that class of drug makes one very photosensitive - was his doctor aware that he would be spending as much time in the sun as he will be? He needs to make sure that he is putting on lots of sunscreen with at least a 30SPF.
I am not a medical professional nor may this be construed as medical advice, but if it were me, I think I would hold off on the accutane until after the summer.