Hi Uther, I'm no expert by any means but after having removed the seat it was easy to make spacers, I would have been worried about countersinking a hole for the bolt as I think you would have to go right through the floor to get the required depth, also I only needed to remove one seat, made two sets of spacers (four spacers per seat) I could then just remove the bolts, slip the spacers under the second seat, replace the bolts and retighten, job done, no holes in the floor.
Ian
