Any RV store should have replacement locks that will replace the twist lock; however, they use a very commonl key (as all the storage doors on your Airstream also do). You can buy the off-the-shelf locks and have a locksmith re-key them.
John W. Irwin
2005 Classic 28 "Sabre-Dog III"
2013 Silverado 2500HD Duramax/Allison LTZ
WBCCI #9632, TAC TX-10