1) "MY" opinion is not much if any structural support can be accomplished from above the floor with the simple design of the seat riser, sparsely spot welded to the floor.
2) There are likely more AD trucks on the road right now without the seat riser in place, than those that do (stock versus modified).
Fur is about to fly now... smile
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission