I don't know if this helps, I have just returned on Saturday from Independence of the Seas. It was great, and there were a lot of disabled and wheelchair bound people on board. While there are no "high" sunbeds, there are a number of sun chairs - which are made from the same stuff as the sunbeds, but the same height as a chair - you should be ok with this. Have a great cruise.
I have just returned from Independence of the Sea and although there were numerous sunbeds onboard i did not see any that were higher off the ground.