I think hiring a driver rather than taking the train might be an interesting experience. Pay the premium in 1st class (train) for the "observation area"
and get to the station early. I enjoyed the train albeit that was my 1979 visit
A more current story is in the second post of
my trip report where we picked up our RTW tickets.
Just remember ***** is not everything.
But I will agree than Colombo can be crowded.
Happy wandering and enjoy
WF