Just a follow-up on this. I sent about a week ago a letter asking to reschedule and explaining my work travel life in June and July and that perhaps a date in August would be better.
I also set up an infopass appointment and just got back from that.
They were very nice, respectful, and understanding of the issues and scheduled me for a date in August and that I should expect the letter soon. I think it helped that Manchester NH is a very small office, but I guess it never hurts to ask politely.