Hi, at the Spanish spaniel show, they were showing puppies as you described
"trimmed back where it would be docked, tip the end and fan the feathering (like a setter/retreiver)"
and the top "stripped" back in keeping with the topline.
This has caused me lots of problems as well, as the long tail is quite new here, only obligtory in 2 regions, and I haven't seen may other pups with long tails until this last show. So we've been showing "al naturel", thinned out with the thinning scissors along the top because it was resembling a "loo brush" and tipping the end. Now I will trimm back where it would be docked as this certainly looks neater.
I think everybody here is watching everybody else to see what looks best! We are all on a learning curve here with the tails, and as for holding them when stacking, there are all versions from holding like a setter, to not holding and to stuffing the tail up one's sleeve
Shelley in Spain