For the first time, I'm going to have to say it can't be done. No disprespect meant to Yeinson, but that model is just not workable. The seams are so convoluted that there is absolutely no symmetry to speak of, aside from the pockets that are essentially free floating, and the back panel which appears to be there for little more than to be a scaling aid. The upper pelvic region looks like a dozen small surfaces were just randomly pasted in not to fill gaps, but just to cover over them. You said that the sanding on this would be minimal, but I'd have to wager it would be the opposite; so many pieces are doubled over, so many redundant surfaces overlapping and criss-crossing all over the place, this thing would be a nightmare to have to smooth out.
Considering what it is, and how rather simple the overall shape of this piece is, I'd say the best approach would be to free-hand it. That seems to be the popular advice given when it comes to the cod pieces anyway, so that you know it will fit comfortably. The only "comlex" work on this would be the pockets, and I'd imagine those would be simple enough to do, especially if they're only used as decoration. But even then, making them functional would still be easier free-hand than trying to work with that model. I'd rather have to unfold a Skirmisher's head with fully rendered plumage than try to make sense of that thing to be honest.