RLK, what we do not know is how difficult it is to insulate the suction line, only that he stated it was difficult, and we also do not know how important the water droplets are.
We do know that the inlet superheat needs to be dropped. If the suction line practically can not be insulated, and water droplets are an issue, then we have superheat the vapour, this can be achieved by placing the TXV bulb on the outlet of plate 3, adjust TXV as stated, there will be sufficient mass flow to freeze the last high temp eutectic plate, then the suction/liquid HX will increase superheat even further. We then need to reduce superheat at the compressor, it is common practice to install liquid injection (OK this normally directly into the compressor via a propriety device)
If he can insulate, then no need for liquid injection