Tiller extension

[lightning]

What's the best tiller extension for my Mercury 6hp 4 stroke outboard?

I thought this would be easy but there's all sorts on ebay, fixed length, telescopic, from 40cm to 200cm. Plastimo seem to be common at £30-35, but there's a telescopic 40-60cm one for £20 from a company called "Pacer Marine".

Can you still operate the throttle twist grip OK?

I'd like to sit further forward in my Zodiac 285s, on the seat if possible, but this would probably mean having one hand behind my back to operate the tiller.