There are now available raised height toilet installations which allow for easier access. Coupled with grab rails that can be fixed and/or fold away this allows for a lot more support and stability.
Vitra Comfort Height Close-Coupled Toilet
On the right is an example of the Vitra Comfort Height Close Coupled Toilet with cistern. You will see by the standard toilet next to it that it is considerably higher and therefore easier to use.
This especially designed toilet/bathroom fixture fits unobtrusively into a normal bathroom and removes the need for the plastic seat height extenders - without anything to measure it by it looks like a standard toilet.
Below is an example of an Impey Snowden toilet cubicle.