I just received the new rail kit for our new truck. After seeing the rails ripped out of a friends truck when they had wreck last year, I went with the 10 bolt rail, and would highly recommend it to any one else. The four bolt uses 4 separate angle clips bolted to the frame. The 10 bolt uses 2 solid plates bolted to the frame. 10 bolt is the top image. 4 bolt is the bottom.
View attachment 43181
View attachment 43180
You're referring to ours, I'm sure. Ours were the top ones shown in your pictures - the "10 bolt" ones. Eight of the ten bolts go through the frame-mounted pieces. The other two are through the metal bed with nothing more than probably a washer or two to spread out the load.
For the OP, here's what our 10-bolt hitch rail system did when we t-boned a minivan at about 40 mph:
Here's the end result:
Not trying to scare you away from the Reese mounting system at all. If anything, I'd recommend the 10 bolt system over the four bolt system for reasons such as this.
Fortunately, our fifth wheels have a lot of metal in the lower front that worked to prevent the trailer from going any further forward. Also, our trailer is currently in the shop being repaired (Lippert) and according to them, it is an easy fix (total estimate, minus a new pinbox, was under $4k).
There's another recent crash thread on here where the top plate of the hitch broke loose from the frame and sent the trailer down the road by itself. Every crash has many potential outcomes. If our hitch had stayed solid in the bed, there probably would have been a different result - possibly worse, probably no better.
At any rate, go with the 10-bolt and make sure they use the recommended bolts (Grade 8?). The correct bolts should come with the kit.
Edited to add: This was an almost new Reese 20K hitch and the trailer was right about 16K. The mounting system is rated to 24K.