Difficult but serious question

A close friend of mine is a recent widower after 38 years together with the last 18 years being home bound care taking. It has been a long and difficult journey. Today he said that he would love to go on a camping trip with us as it has long been his dream. We would love to share this experience with him. However, he is nearly 400 pounds. My first concern is his safety, my second concern is his comfort. My third concern is if he can actually fit through the doors, manipulate his way in the tight spaces, sit at the dinette, use the bathroom... I have a 25 ft TT. How can we make this work? Any suggestions? Is there anything I need to be aware of? We're really good friends and can address the necessary issues but I want to be sure to treat him with the caring, dignity, and respect he deserves. Thanks in advance for your help!