WOW, quite a few days and no one has replied. That's sort of discouraging. But, it's probably a tougher question than it first seems.
I don't have a Suburban but I do have a 92 Vandura that also has a rear unit. I don't have any idea how similar the two designs are but I would be willing to bet that they are very close given how GM has always planned for a lot of interchangeability. (Oooh now THERE is a big word!
)
When you're thinking about retrofitting another unit into your 'burb, take comfort in knowing that all the lines are at least flexible. There is a rather important looking connector deal that bolts right to the back of the compressor on my rig. It splits the refrigerant path between the forward and rear units. It has a muffler type of bulb in the line that goes aft that they say can't be flushed. But the rest of the unit can be if you want to do that.
Also, the entire rear unit on my van looks as though it will come out as one assembly but I can't say for sure. I'm only saying that it
looks that way. Hopefully, it would go easier than first appears.
You may seriously have some work cut out for you if you have to fabricate anything but if it were me, I'd go for it. That's because I LOVE LOVE LOVE AC and HATE HATE HATE it when it doesn't work! Your kids deserve to be comfy. My own ride is a mobility van that I use to carry my parents' wheelchairs. A couple of years ago, when the AC was on the fritz, I had my folks with me on a trip down the interstate. Mom was riding shotgun but Dad was in his wheelchair in the back and got seriously overcooked before we even realized it. The paramedics had to come and haul him out on a stretcher because he had passed out on us. This got him a couple days in the hospital and scared the absolute crap out of Mom and me. You can only imagine how we felt when we pulled into our driveway and found him unresponsive. So, I don't know about you, but I get REAL serious about keeping my van's AC running both front and rear. My folks are both 86 and I'm not losing them without a fight. I want them around for at least another ten years.
So anyway, the reason I say all of this is that being able to use parts off of a Chevy/GMC van might give you some more search options. Good luck with this. I'm really interested in how it goes. If I lived closer, I'd come over there and help you get it working.