I don't see why it should not work.

All you need is an amplifier with a gain of 1 for the LSB DAC and an amplifier with a gain of 256 for the MSB DAC. Now, when using a high gain amplifier, you need to worry about noise. But you mentioned a 1sec update rate, so a very strong low pass filter on the MSB + LSB DAC outputs may do the trick.

The R2R ladder network seems a good option as well. But it is better fun to play with the analog circuitry if you have the time for it.
Of course other considerations should apply to the design such as : offsets, gain non linearities .....


Good luck