You might add a chord that switches to a different layout (cycle through layouts), have this layout empty (except for the cycle chord) and cycle back to your desired layout afterwards.
The empty layout wouldn't accept any button presses, and your cycle chord should probably be a chord that's hard to press accidentally, e.g. T1T40M or so -- but this would also be hard or impossible for you to press with just one hand.
For me, the standard sleep chord T0T2T3 is kind of impossible to hit with just one thumb, but when I want to put the device to sleep, I'll take it off my hand afterwards anyway, so no issue here.
