Malware on your computer has to run from the DRAM like any other program, so even if you come up with a hardware RAM cloning solution the currently running malware will still be written to disk along with anything else in DRAM.
Not sure why you are so concerned about malware/virus protection in this DRAM cloning device.
If this was for windows I would find out what the hibernation file API is and see if you can call it without the shutdown afterwards. Hibernation writes out the current contents of memory and can also restore it at a later time, though I have no clue if it's possible to make more than one hibernation image and load them.