If you have a few more shekels in your pocket, consider moving up from bungees to a Forespar tiller extension with a "lock box."
I never had great luck with "soft" solutions like lashings. If they're tight enough to do any good, they're too hard to snatch off when quickly needed. Of course, I've probably learned a lot about sail trim since then.
In reality, these days mostly I use the tiller pilot on "standby" as the tiller lock, but now that I've adopted a wind vane, I'll need to go back to a purely mechanical lock - and figure out some way to rig it with the tiller flipped aft, in some way that doesn't interfere with the traveller. I wonder if a shorter tiller is in order?
Oh, the other thing you can play around with, with a tiller and bungees is "sheet to tiller steering." Free self-steering for Rube Goldberg fans!
This will make my life much easier moving about the cockpit and short stints away from the tiller as I single handle much of the time.
