Hi Andy,
Picking up late on this.
In case still of interest
wrt berthing: I have a lot fun and games berthing since on a short finger pontoon in a narrow fairway with tidal flow, and the BC26 is easily blown about!
I use a bridle instead of a spring both for bows-first and stern to.
For bows-first, effectively a stern bridle: warp fixed to midship cleat on boat, and stern cleat on boat (either fixed measured length or with warp over stern cleat loose and ready to be hauled in), warp coiled and thrown / dropped over first cleat on pontoon, motoring ahead to bring into pontoon etc
Stern first, technically a mid-ship,bridle I think? , again warp tied onto midship and stern cleat on boat (measured & marked to stop stern 1m short of cross pontoon!)and dropped over first cleat at end of pontoon, reversing to draw into pontoon. It is easier to approach this way (stern to) but longer length of warp means more susceptible to be blown about by the wind.
Best,
Peter