I worked on a woman recently who did not fit in the chair. What I did was improvise by having her sit in a regular chair and then rest forward, as much as was comfortable for her, onto a desk. We used some cushions for her to lean/rest on. This worked perfectly and she wasn't smashed into the chair and she was able to relax.
I was able to get to all the areas that needed tending in that session and she was VERY happy. This was also her first ever massage and I was glad that I didn't traumatize her or make her feel poorly about herself. I didn't say to her that she wouldn't fit in the massage chair, instead I said, let's see if we can make you more comfortable by sitting over here with some cushions. I think she was very relieved that I wasn't going to ask her to try and cram herself into the massage chair...
