When I first tried the P&H Delphin I was impressed by all the usual things: its comfortable ergonomics, its stability in rough water, its manoeuvrability, its surfing, its rolling, its behaviour in winds... but I really couldn't wait to put a sail on it. Those hard chines at the bow are just asking for a sail to provide the drive to push through the waves in front!
I mounted the pulley for the uphaul/fore stay on the front deck line recessed deck fitting (RDF). The pulley for the sheet and the back stay went on the front deck elastic RDF. The existing side deck line RDFs were just too far behind the mast to provide support when reaching or beating so I mounted two stainless steel saddles on either side of the mast and attached the side stays to them. If you were only interested in downwind sailing you could use the RDFs and do away with the back stay.
I mounted the sheet and uphaul cleats in front of the cockpit and to either side of the 4th hatch.
The ideal position for the mast base was just forward of the compass mount but the foredeck on the Delphin is peaked. Purists will be horrified but I just fitted the mast base to the right of the mid line on the flat part of the deck secured with two penny washers to spread the load below deck.
I use the same mast on my Nordkapp LV, which does not have a peaked deck. The side stays were therefore too short, so using bowlines, I adjusted loops of 2mm Dyneema cord through the saddles and clipped the snap shackles into them. If you only use the sail on one kayak you could clip the snap shackles directly through the saddles.
The beauty of the Flat Earth flexible tendon universal joint is that the mast is still vertical despite the mount and...
...the wind couldn't tell the difference!