Hi. I sell a ton of 50mm wheels. I recommend 80mm tubes for those that don't want to use extenders. I recommend Vittoria/Tufo style removable core extenders for most. It allows users to use standard tubes, and will allow them to most likely make use of other's tubes in the event that they experience multiple failures on a ride.
These also come with teflon seals allowing for the whole system to be sealed without use of teflon tape.