Not to talk you out of using coleman coolers, but if getting your moose de-boned and butchered turns out for whatever reason to not work out as planned - I'd be tempted to look into building one big crate type box out of plywood/2x4s and line it with styrofoam. A standard 40" x 48" pallet would be a good base, just nail on some sides and a top. 4 "on the bone" quarters will easily fit inside, along with the rest of the meat. Would just need to bag the ice blocks so water doesnt get on the meat. Just throwing this out there.
For size reference here are a few pics from a few of last years clients. All are Alaskan bulls
40x48 standard pallet
This cooler I am guessing to be 60 qt (?)
I'm not sure of the size of these totes, but all 5 are full of boned out meat.
The pallet with the boxes with green stickers is 2 bull moose all boned out meat. 40" x 48" and about 36 inches high.
These boxes contain the de-boned meat of one bull, although obscured by the antlers. For size reference that is a 64" rack.