I can hardly believe this works, but it does and the results look great.
The Type F sleeper coaches by LS Models have close-coupling cams, much like all modern Continental stock. You can fit Kadees but they tend to collide with the buffer heads on sharp curves, especially going through a reverse curve. One option for Kadees is to cut off the trip pin and mount them upside down. This works well enough within sets but the coaches still sit too far apart.
Anyway, looking closely at the models, the corridor connections extend a little beyond the buffer heads. So at the limit, closeness of coupling is set by the corridor connections not the buffers. I discovered, the Bachmann drawbar for their class 101 DMU brings the corridor connections together perfectly:
The inner buffer heads are just touching each other, but buffer locking does not occur. On Shelf Island, the 450 mm radius curves are inside a tunnel and in the fiddle yard. So I can have good-looking train, which still gets round the corners on my layout.
The limitation (there has to be one) comes on a reverse curve, where the ends of the coaches try to side-swipe each other. For me, this occurs just outside the tunnel, usually hidden from view by a retaining wall. Here are two Kadee #19 couplers, pushed to the limit at the most difficult location on the track:
The drawbar is long enough to let me haul the coaches here, but a fraction too short to allow reliable propulsion. I think, a drawbar 1 mm longer would be ok but this would spoil the closed-up look on straight track. There is no need for coaching stock to visit Fairport, so I will accept the close coupling as it is now. I have set up a rake of three coaches, this is just about possible to pick up as a single unit. Using three coaches and not four also means, if I ever get a Mk1 brake composite and the fourgons, a complete Night Ferry train will fit into a 1200mm TrainSafe tube.
The drawbar is Bachmann p/n 36-066. It is relatively expensive to buy because it has electrical contacts this application does not need, but I happened to have two to hand from my class 101 DMU, kept from my 00 days. LS Models specify a minimum radius of 450 mm for these coaches, so I suppose the use of the Bachmann drawbar demonstrates the limit of their close-coupling mechanism rather well.