Washing the feet in ghusal

Is it O.K to wash the feet while standing upright during wudhu without using hands to make khilaal between each toe, because I am over weight. I just thoughrally wash my feet by spreading my toes fingers while standind, I do that only when I sit at the masjid Wudhu Khana. While at home I make the wudu in a standing position, because of the over weight, it's hard for me to sit in the bath tub to wash my feet using fingers. Please Advise me for this.