Yeah exactly! Theres a nut for the ground mount and then another pretty shallow one more towards the front of the vehicle. A good idea would be to slot the mount holes of the bracket to make it easier to install.
I made a bracket similar to the mount that guy offered. You can’t really tell but it mounts to the bottom where there were some bolts mounted into nutserts. It’s definitely got room for improvement but there’s some usable space in that area.
If you truly go under the rear pressure specs from Kings alone, when you sensor lift it that will increase the force from the hydraulic system to compensate for the lift. So, you could get back in spec.
A minivan is a purpose made tool that functions very very well for its intended purpose. So is a Land Cruiser, but to me it seems your purpose is not aligned with the LC’s.
Save yourself weight and money, go with 1/2” birch. 3/4 is overkill. Also I can never find 4’x8’ sheets of Baltic around here, it’s always that approx 50”x50” size, that may throw a wrench in this cut sheet.
I would guess the rate of speed decrease was not enough to trigger the sensor. This looks very similar to an overlap test which older cars do not handle well. Sort of like a glancing blow where the sheet metal slowed most of the deceleration, rather than a rigid frame. If the impact was greater...
Good on you to do some basic calcs. Essentially, a higher section modulus means for a given moment (force applied at an distance), there’s a lower internal stress on that cross section. So, bigger section modulus means less stress. Stress is bad, but you know that cause you’re a paramedic :)