In my Duo I drilled hole into seat at critical point and straight down through the Hull as well. Installed guide tube about 2cm ID,glassed to the inside of the Hull ending up at Seat level with loose wind closing flap on outside of Hull. Used a small teflon coated aluminium Tube about 50-60cm long to push through the guiding Tube. At the business end of the alu tube,connected piece flexible tube with a quick one way walve connection to the Condom. Also put a stopper (lid) on the guiding tube when not in use.
1. No contamination on glider as evacuation is quite some way away from Hull i.e. 40cm
2. No chance of freezing as tube is kept in the glider
3. Suction is so great that every last drop is removed from Tube ie. no mess
4. Use the Tube only when required, ie do not leave permanently in during flight.

However a word of advice when using this System, the Condom should not be fitted to close to the Tip if you are not circumcised as the Suction could pull your Foreskin and block the outlet on the Condom.