Taking a person-formerly-known-as-a-WRAF on an MRR borex once, the question arose as to how to provide a relief device, should she need to 'go'.
This was solved by acquisition of one of those huge oil replenishment funnels bodge taped to a standard Vulcan pee tube, entitled the 'WRAF adaptor', which was placed in the visual bomb aimer's position. Using it would have been little fun for her, as it was immersion suit time of the year...
One sight of the thing was enough to persuade her to 'go' immediately before flight and not to drink anything during the flight.
All went well, we spotted the odd boat and she was happy enough.