I built, and slightly modified a Caldercraft Northlight a long time ago.
The kit went together quite well . If you look at some pics of real puffers, however you will see that there is a rubbing strake too many on the kit hull.
For a more realistic appearance the lowest one needs to be sanded off.
Another point, and I notice this on many model puffers,not just the Northlight kit, is that the black hull paint is carried far too low.
Certainly the well known "cruise puffer" Vic 32 has black to the (unladen) waterline, but she is not at all representative.
Have a look at
www.river-clyde.org.uk/puffers.html and you'll see what I mean.
Please note I'm not criticising how you have finished your puffer models - that is up to you, but am just passing on some information on how they really looked.
Pic attached of mine which represents arguably the cleanest puffer on the Clyde - the 1903 Saxon, owned in Millport.
Best Wishes
Douglas