Get an airplane with less than 1 hours fuel on board

Get an airplane where you dont lie on your back.

Get an airplane with a piss tube (buy an AT6)

I can understand how a male could use a roll on catheter, but what is there for the females? Except the wet towel off course... I don't think the owner would like my wife peeing on the nice cushioned seats :)

Currently there is no issue as were both young enough, but who knows what the future will hold...

There is no shame in being prepared. Can the fancy seat cushions be covered or removed? And wearing a nappy is customary for all astronauts who may have to wait overtime for the launch....The only problem, if you are flying with strangers, is overcoming all those well taught inhibitions and letting it go!

What IS a shame is flying badly because you need to pee, or crashing and rupturing your bladder if you impact with a full tank....

In the mighty Tin Triangle, 'relief facilities' consisted of a football bladder connected to a metal top with a hinged flap to prevent what had gone in coming out before landing.

Not much use for the ladies though.

One day we took a visiting WRAF officer flying and explained that the facilities hadn't been designed with ladies in mind. However, we told her that a 'WRAF adaptor' was available - this was one of those huge funnels normally used for adding oil to a Chipmunk engine, which would be inserted into the metal top of the pee tube. Fortunately she realised that this was a leg pull and that the message was 'go before you go', so that the problems of getting out of an immersion suit before taking aim were averted! And she enjoyed her Vulcan flight without any discomfort.

caffeine doesn't just cause pressure in older people, it's used in medicine to increase the flow even for newborns, so as others have suggested, definitely stay off the caffeine

I once had a share in a PZL Cobra glider which came complete with a black rubber elongated receptacle attached to the pee tube which the manufacturer assured us was suitable for use by either sex.

Incidentally, one of the female members on the club who was also a nursing sister told me that she relied on grown-up nappies (just like the astronauts).

I'm not in a position to take female friends / girlfriend(s) on any long distance X-countries so I've never worried about it.

But in case you have to:

From a well respected Woman's Gliding Champion personal website:
http://www.freeflight.org.uk/plumbing/

or the bottom of the page:
DG Flugzeugbau: To Pee Or Not To Pee