A couple things to bring up here.
I have done a few of the above mentioned, ditched a fixed gear single after an engine failure and operated multi turbine seaplanes in the middle of the ocean.
The sea can do many things in a short period of time it is not the chop that is dangerous it is the swell, and the frequency of the swell.
Day time you can pick it no problem, and always parrallel it, always always, Take the cross wind, full opposite deflection and get your feet working because trying to go straight into it will bend the aeroplane, just go and ask any cessna rep about the fire wall mod available for the caravan and what floats mean to your warranty.
The question of night is different, you have to take into account many things and it can be done ie, sunderland and cat ops in WWII.
However in an emergency situation you a modern FMC in a transport category jet will have a wind direction and using that and the knowelege that wind and swell coexist, then then put the wind at 90 degrees and commit to an approach, Full flap to 20/30 ft RA, and then pull the nose up to slow in ground effect and stall in.
These would be the best options in an aircraft not designed for water ops the best option is absolute min speed at water entry.
Ask any seaplane pilot who has witnesses an anphibian land in the water with the gear down.
IHD