Midwest Industries has released their own Internal Light Mount end cap for their IWI Tavor rails. It is designed to hold lights with 1″ diameter tube bodies inside the handguard.
Interestingly, it can also be used to mount a Surefire Mini Scout Light completely contained within the handguard. MI promises that this will come in handy for a future release.
These will be available soon in both black and FDE. Check out Midwest Industries.