My niece used to camp with us, since she was wheelchair bound I had to carry her into the TT whenever she needed to be tended to, while she never complained it was an issue. The fit through the entrance door was tight and I had to ensure she did not bump an arm or leg as we squeezed in.
When we started looking for our next TT I inquired about the possibility of a lift being installed and unfortunately the TT wall construction was the issue, it would not be strong enough.
I was advised a class A or Toy Hauler would be a better option.