Your description isnt really correct.
There were around 13000 day (Also known as "Joey") on the BCN at the peak, both of wooden or iron construction. Many were double ended with provision to hang the "ellum" (rudder) from either end, all were fitted with steerers platforms. Some would have a bulkhead between the cargo and the steerer. the single ended boats tended to run longer distances and could have quite a shpely bow. Approx 50% of the boats had some sort of cabin, all these had a stove with some sort of bench seating, the odd few had cupboards and bed provision.
There were many distinct types, Bantocks built three distinctive types, the early being single ended wooden bottom and composte sides (wood and iron) with a shapely bow, the next roughly the same baut all iron, the latter more functional. Hickmans built a very rudimentary boat double ended, then Harris of Netherton built very cheap boats using second hand plate often sporting filled in portholes. The LMS has shapely boats built by Yarwoods for interchange traffics whilst the GWR used a fleet shared with Bantocks. the wooden boats were also highly distinctive, those from the massive fleets of Yates (400+) being sub leased to other firms but with distictive carvings denoting their origin in the breastoak. Ernie Thomas boats were the same.
When towing in the main the mast was "stepped" to one side to assist the steering unlike conventional boats which had upright masts.
The livery and style of decoration was completely different to the main canal system, quite how this came to be is a mystery but boats were painted in a manner more reflecting mediterraen styles.
The cargo could be anything, coal was a main cargo but the boats carried anything that needed to be moved, from liquids to pottery. On the 473ft level some boats were built in excess of normal dimensions being up to 85ft long and over 8ft wide, these were known as "Hampton" boats and moved coal from the Cannock coalfields.
The boats were treated as such, not as skips and docked regulary, they had a rough life but needed to be efficent and functional. It is a pity that many railway modellers ruin their layouts with ill presented canal scenes, the canals and the boats were a as precise in detail as any loco or region, the day boat is unique in that there were so many they often would be disposed of into maintenance use and as such can appear a long way from home, it is not unusual to see one in grand junction canal pictures in the London area or on the Thames.