Hello,
Sorry that I don't really have an answer for you. So we used this protocol to analyze skeletons of both embryos and adults (more than 3-weeks old). We always used 10% buffered formalin for fixation --- I'm not quite sure whether ethanol would serve well. Maybe it can do the job as along as you clean up the tissues as much as possible. Please let us know if you will try ethanol-fixation for adult skeletons, and we will add your input to this protocol then.
Thanks,
Peichuan