I have not done disaster nursing, however I did work for 10 days at a clinic in rural Mexico. Each of us in the group that was going worked hard for a year to raise the $$ to send us and begged, badgered and pleaded for supplies and good used clothing. Each of us took a backpack with our clothes and two big suitcases full of supplies. We slept in the clinic, which was very crowded, and people from the community came in to cook for us. There was no hot water, so morning showers were definitely short & invigorating.
Each evening we would hold a teaching session for the community -- since only 3 of us spoke Spanish, I had to translate my share (and it had been YEARS since I'd used it -- was I ever rusty! but it was apparently understandable and the folks there got a big kick out of my fumbling). We were split into teams, and then each team would be assigned to the clinic or the community. We did Pap smears, visited disabled people, did assessments, ECGs (the machine was so old it only had the grounds and one other lead...so we'd move it from site to site and label it), more teaching, and then made notes for the MD, since he'd see the people who needed more than we could give them. I didn't get to do quite as much medical as I wanted since I was translating, but that was OK, too.
I got to do some brief counseling with one lady who was probably suffering from PTSD and depression, and also did a digital rectal exam on an ancient maiden lady who could not bear for the male MD to do that to her (he stood behind a curtain and I described what I was feeling...weird, but it worked I guess).
It was a very rewarding experience, and I hope to repeat it some day (hopefully after my youngest is in college -- he's 15 now, so not that much longer!)