Hello @Jakob T. Thanks for the question. Couldn't give you a batter answer than @Frederic's.
I would say that if you (or the garage) don't have enough time to check fix your rear bumper, we'll find way to minimize any possible damage to it, if any may occur at all. Many Pajero's such has yours have come into the desert with Carnity, and exited unscathed 😁. Our philosophy is to teach off-roading skills so that members learn to maximize their knowledge based on their stock car, before they move on with modifications.
Frederic's suggestions are just to better protect your car. I would add that it's best to remove the rear bumper even before you consider a rear skid plate, at virtually no cost. If you'll enjoy your outing, and wish to further pursue off-roading, than you can go one step further.
Looking forward to seeing you.