Likely going with two systems
I think I will be going with two independent systems. My two boxes are about 8' apart and with two systems I can put the compressors in different locations to reduce the heat problem a bit.
I got a quote on a Seafrost system that used one compressor but it was just too much $8200! I have installed a Cold Machine and it was not too bad to do. I might go with Adler Barbour again although, from what I have read their customer service is not very good. Will not be very easy to remove the existing system though. as there is a lot of wiring and piping to deal with.