I only ever flew on Victor tankers, so most of my flying was at high level when the chances of a successful rear-crew abandonment were at least reasonable. I dont think any of us really gave much for our chances of getting out and surviving at low level (say at circuit height) but this was just one of those things and I dont recall worrying about it much.
Having recently sat in the nav rad's seat in the Vulcan at Newark Air Museum I must confess the idea of stooging around at low level without a bang seat does not appeal, plus I found it very claustrophobic after the more "open plan" Victor.
Btw I concur with the stowage of pins - definitely on a bracket on the side of the seat, not in a drawer, and it was the nav rads job to arm/disarm the seats if operating away from base without a crew chief.