It will be everything to know how much of the impact was transferred into the unibody. The rear is a solid axle beam, which is unlikely to have been damaged. Further, there's no alignment adjustment possible for the rear wheels, so you don't have to worry about that at all. The biggest issues I see is NOT the rear liftgate. You can probably get one from a dozen junkyards near you, maybe even matching color/year, for under $500. Depending on the junkyard, it may even be a "loaded" door, which includes everything from the interior panel/trim to the lights. Since the damage doesn't look too bad (only one photo; not seen in person, so, YMMV), I would bet most of the impact was taken up by the actual bumper and brackets, rather than getting transferred to the chassis. If that's the case, replacing bracket to bumper cover would get you back on the road. All that said, the big issue is, if the trunk latch point has pushed back/sideways from its precise factory location, it's possible that you will end up with the van persistently or intermittently thinking the trunk is open. If it does that, it will have a battery drain which will keep the ECU awake and kill the battery overnight. If it were me, I would get 3 quotes from reputable body shops, see what the adjuster says about the damage and value, and then proceed with what you think the best option is at that point. If you have to buy the van back for $500, get a salvage title (which costs money in some States), spend $500 on the new trunk, $500 on a new bumper, cover and brackets, $500 for a color matched paint in rattle cans, do a poor-man's chassis straightening (come-along between a tree and the trunk latch), and end up with a van that has no monetary value, even if it drives, and needs a daily jump, I don't know that I would do that. On the other hand, if you find the right color in the junkyard, replace the bumper brackets and everything else is aligned right away and that lets you pocket a few hundred dollars from the insurance payout, by all means, go for it!
