I've never sat in the L4 front seat but agree the rear is quite comfy.
I didn't realise that there was an official pilot's seat in the Cub family,but do now!
So rear it is on the L4,solo or with passenger.
Out of interest I will check the height of the seats next time I'm over there.
I just checked the original Pilots Flight Ops instructions,and apart from stating solo from rear it does not mention pilot from rear at all times,also mentions observers "desk" behind rear seat so it is rather confusing.
Lister