You want a one bulk train idea? Here you go:
Eliminate all of the Silver Service and the Auto Train. Add the autocarriers to the Capitol Limited. Open an auto loading terminal in the midwest somewhere (see
Research - Florida tourist originating numbers). Run the Capitol Limited through D.C. and extend it to Florida splitting at Orlando with half going to Tampa and the other half to Miami. Make the busiest stops and add/remove car carriers at Lorton and Sanford.
Run a separate coach train between Miami and Tampa until Brightline comes on board. Provide easy across-the-platform transfer in D.C. from a NEC regional that provides through baggage service from Boston.
There's one bulk train for you.