Since what you really seem to want is a timed start-of-charge, and a charger that can monitor individual cell voltages, it sounds like it would be much easier to simply create a timer and wire that into the start button on an existing RC charger.
A slightly better way would be to take a bunch of separate single-cell chargers that have the cutoff limit you want, and wire them all to a power strip, and use an existing wall-outlet lighting timer to turn the whole bunch on at once. This way there is no wait for balancing to occur, which on smaller RC chargers or other bulk chargers could take hours. Every cell (or group) will be individually charged to the proper voltage, independently of the others.
If the chargers tend to leak current back into them when off, then you could do the more complex method of adding relays or solid-state switches between the chargers and the cells, and power them off a separate wall wart also plugged into the same strip. Then they will turn on and connect only when the whole charger setup is turned on by the wall-outlet timer.
Either of these methods will accomplish the main part of your goal, to charge them only just in time for the ride.
To do the other part--storage-level charge, you could add a simple voltage sense to each cell, basically just like Methods' HVC/LVC units, so that they are triggered by the storage-level voltage you want to stop temporarily at. Then run that to a relay unit that turns off one of two ac adapters that power the main relay units that cut the cells off from the chargers.
Then, you'd not use the wall-timer on the entire set of chargers, but instead only on the other ac adapter for the relay power supply. Thus, once the timer kicks in, it turns the relays back on and they finish charging up to the charger max voltage.
Much easier than all that programming and power supply design stuff.