Mary,

Can you fix the skin overnight? (Although 4 hours is probably
adequate.) I usually let my rodent tissue sit in 70% ETOH for at
least a couple hours before going through a processing schedule
of 30-45 minutes per solution...I would go with 45 minutes if the
skin contained a lot of adipose. I must also confess to never
washing the after the fixation step.
Good luck!

Lorraine 
P-Bio Histology