The experiment with Kadee couplers as detailed in an earlier post had to be terminated as the hook of the coupler kept catching on the points on the site causing derailments of the wagons when being propelled. Back to the drawing board then, but i think i have found a solution. The problem with the default hook couplers is that they decouple from the loco when going on bumpy parts of the layout, this is because the coupler in one part of the train momentarily rises higher than the preceding part of the train causing the hoop to lose the hook. By bending the hoop a bit i've found this problem has been solved. At least its promising...
Plymouth No. 17 has no problems though even though its coupling to its wagon train is very simple. Sometimes simple is best!