So I found the bottom part of Bulstrode the Barge in a second hand shop. The scale seemed to fit 28mm so I bought it and brought it home.
Photo taken online.
This is the part I bought for about 2 EUR. All loose parts were missing, so no superstructure.
After failing with a metal saw, I resorted to brute force, using a plier to flatten out the bottom.
I glued the boat to a piece of cardboard and covered the ugly edge with silicone window filler.
I cut out a small cardboard bridge and found a few pieces of plastic sprue to use as a mast and a trawler winch. I also added a piece of cardboard as deck. After that I painted it in light blue and rust covered white.
Anchored in a pirate hideout in the Blood River delta.
Setting out looking for containerships disregarding the UN imposed safe route.