So I'd also mentioned about a cheapo throttle restraint (too much of a stretch to call it cruise control).
I used an enormous cable tie, cut it down to correct size and secured it to the inside end of the twistgrip. You push it down onto the top of the front brake lever & it stays in place until you twist the throttle again. Size-wise, I think it's 12.7mm wide and fairly rigid, so when fitted stays in place and secured tightly doesn't seem to slip. I suppose eventually it'll wear a bit but just buy a six pack of them - they're pretty cheap.
You can then jam a very thin, small screwdriver head into the cable tie's teeth which allows it to loosen and come off, so it's removable and re-usable.
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Works pretty well.
Alternatively, you could use a fairly long, thin jubilee clip on the twistgrip. It'll do the same thing, although the metal might be sharper against your hand.
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Cut-down cable tie compared to a standard size one.Â