TRSS,
No goon suit in the good old days.
IIRC the Co was wearing the old style rubber buttoned long johns and probably underpants under that. Then an AVS over that and his Mk 4 flying suit - the shiny fabric blue/grey job.
Of course he had to unstrap from the bang seat and seat straps which was probably what really detered him.
Now if he had been wearing a pressure jerkin and g-pants it would have been impossible. We only wore the jerkin on occasional trips but it was something else again. It had a diagonal zip from one leg to the opposite shoulder. The only way to use a pee-tube required you to stand up and unzip and slip it off your shoulder.
The immersion suit to which you refered was easy peasy compared with the Mk 7. This was a two piece job with the seal around your mid-drift.