Simon.
The only time I ever did any 'coopered' work, was a bow-fronted pine corner cupboard for a dealer.
To make the doors, I built an accurate 'former' of MDF, clamped it to my bench, and got out a Record No. 6.
I hadn't a clue about coopering, but I could make a good rubbed joint. So, I merely planed a bevel on the edge of the first lath, and then fitted the next one to suit. I continued like that until I was knee-deep in shavings and had two curved doors. I'm sure all the bevels were different, but they all fitted properly. I achieved what I wanted without too much trouble, and as far as I know the cupboard is still okay. I doubt very much if that was the proper way to do it, but it worked. I never had any negative feed-back anyhow. The dealer BTW was a friend (Sadly now passed) and he probably made four times the price he gave me, but hey; what are friends for? 8)
The difficult part was removing the 'flats' from the inside curves, but I picked up a rounded sole moulding plane at an antique fair, and did it with that! The laths were certainly a lot thinner than when I started, but that was fine, as the doors looked all the more elegant; well I think they did!
All, that probably won't help, but I can always hope!"
All the best Simon.
John