Brilliant idea to check the yacht listings. I'm pretty sure the pics show a boat that was also converted from a wheel, hence the rounded seat. I think the tiller boats had a flat deck through which the rudder stock protruded. The position of the controls is exactly where I am thinking of putting mine, just because it would be easiest and out of the way. Nice to know it worked for someone else.
It will be insteresting to see if anyone comes up with a pic of a "tiller boat" to find out if PSC had put the controls somewhere else on those.