Hello Atio and Welcome to SMF
Read the instruction on cold smoking with the cold plate, and I just don't see how you can cold smoke, without adding heat. You have to cycle your smoker on & off, and the the chips/chunks smolder for a little while. After a short period, you have to repeat the process.
If you're planning on using one of my gadgets for cold smoking in a Smokin-It Smoker, I would lean towards a 6x6 or 6x8. Your smoker just does not have enough air flow for the AMNPS and pellets to burn properly. Sawdust performs much better.
With the 6x6, you'll get very little increase in heat, and you can always throw in a pan of ice to keep temps down.
The 6x6 or 6x8 will produce plenty of smoke for your smoker
The AMNPS will burn either sawdust or pellets
If you want an AMNPS, make sure you order some sawdust to go with it