The Walthers' carfloat has a faux switch on board which makes loading
a problematic thing. The plastic rails are not a bad idea, since they are
reasonably representative when worked over with paint. By the same token
replacing them wouldn't be a bad idea, but using a flexible cement that would
not have a solvent base which would attack the float's plastic is a MUST. ACC
or some similar inflexible adhesive will fail (even if it doesn't have a built
in lifespan shorter than us, like ACC) because of the differential expansion rates
of the plasticbarge and metallic rail.
The fact that your float isn't floating in water, makes the loading/unloading
pattern moot, but....
So to duplicate reality, for modelling purposes, you would first have the weights
of each pseudocarload (i.e. at this time and place -which reflects weights of
loaded or light cars).
Your conductor/dockmaster will have this in his papers (waybills) and plots the
apron work accordingly. Switchers did use empty idlers cars, but they also
came unto the bridge ramps on many occasions, and also sometimes were
carried from point to point on the carfloats. Currently this is done in NYC
harbor because the operator cannot keep the loco from vandals at one end
of the line, because they don't have a 24/7 manned yard there .
In the past they also travelled, for maintanance reasons in order
to be shopped, as well as when they served a landing point without a local engine.
Non-Railroad carfloat operators were the most likely to find themselves in
this position, but common carriers served isolated private points. If
you plan to have a pike where the carfloat operations are the sink and
source for all the freight cars handled (say, in lieu of hidden yards),
then you might consider using one of the carshunters available, or building one
appropriate to your timeline, as these can be carried easily on the float.
The stock yard operators with carfloat operations are an example of this type
of operation.They also are an example of carrying freight, in their case
livestock on the hoof, as deck cargo on carfloats. So make sure you have a
sturdy safety railings on your carfloats, and you can deliver them to shambles
and abattoirs around your docks. Better yet, to those offsite a few
imaginary blocks away , so you can herd them down the street. Because, that
is what was done in Brooklyn, Philadelphia, and various other places that had
a mounted herder from the shambles, and a Judas goat meet the
barge and lead its cargo through the streets. Not pigs, of course, they were
too smart to fall for this routine.
In loading railcars, they would normally have fully unloaded the float first,
and even if there were through cars going beyond this point to a second
yard elsewhere they would also be unloaded to adjust for keeping the
float level, and to facilitate unloading at whatever was the next site.
So lots of dockside planning went into arranging the cars by weights and
destinations (if there was intermediate stops)in order to safely transport
railcars by car float.
Good-Luck, peter Boylan