Youre lucky, I just did this last month...Strength will not be a problem. We did some dry runs recently for samples and was able to stand (200Lbs) on the corner of the small box within 5 minutes of applying the adhesive. However, we had about 80 boxes to make that were finished on the inside and out and absolutely would have gotten smoked had we used PUR. There are 2 issues...1. The material itself is super thick and sets up fast. You could apply all of your glue and start folding only to find out that you are out of square due to excess glue in a joint. Once you fold the last part in, the 1st is already permanently bonded. = To the trash. You could get real good at it and make a bending jig which would likely solve that issue, but you still risk no chance for any realignment. Just be sure you are using a 91 or 91.5 degree bit to allow room for the material.
2. The stuff dries really fast and not easy to cleanup squeeze out if you need the interiors clean.
I love the pur for quick fixes, jigs, or trim on installs, but for me that's been the limit.
The only way I could see this working well is if you used it on the last piece to connect.