I am also following this post and would appreciate to see your photos on this (for my Hanse 345). 

Thanks a lot. 

If there is some interest here, I will send some detailed photos in a week when I am back to the boat. 

Actually I have two old pictures from when the boat was new because we had a warranty problem (no ply fitted to infill cushion which meant they went straight through a hole ). Picture shows the overview of how it works - basically a vertical facia panel in cabin wood colour which meets the cabin floor attached to 12mm ply horizontally which slides over seat bases. Tracks cut in ply slide over 12mm dowels in the regular seat base - it’s a little crude in my opinion and awkward to drag out but I’m sure somebody could come up with an improved if retrofitting something similar. 

Of course, I’m back at the boat on Monday so I will add some more detailed photos. Just to set your expectations though, there is hardly any changes apart from the dowels to guide the sliding section - there is no additional reinforcement. We had to make some repairs due to this lack of reinforcement so I’ll capture these repairs too so you can identify the stress points and protect against failures from the outset. 

Photos to follow in a few days. 

Unfortunately the 345 is a little more compact and the berth (when pulled out) isn’t square and tapers at the forward end to the extent that one of the inserts has a sharp angle in it to bend around the table.  Hanse agreed as they rectified quickly under warranty. Also, there’s no ply under the settee either so there’s a hole there too when the ply based cushions are lifted. Thanks for suggestion all the same though, as you say if there was a solid base like in the larger boats it would be much easier!