i must be dumb. i don't understand why all the technical wonderment. i would make a simple guess that if you jump it and it lands on one corner, it might bend a little, so, add a rollcage with supports that extend to the suspension points and front and rear ends of the bumper. build the cage such that it will deflect a good hit at just about any corner of the vehicle and any open areas of tube could be relatively easily replaced if bent. there should be plenty of tiangulation in said roll cage and if it were built for Baja here in America, it would have to be built from chromoly tube.

i don't think there's as much math involved as you're worried about. i think it's a lot of eye-balling and previous experience.

this is all just my opinion, because i pretty much operate on eyeballing and previous experience.