our brackets on the '06 were not equidistant on each side to the platform and were off by 1/2" on the bracket mounting "sleeves" on the back of the boat if you took a tape to each hull bracket to the outside of the boat. back in the day, skiers choice, and all boats for that matter, didn't have the best fit/finish out there. we had a lot of crooked pieces around the boat if you really started picking it apart. doesn't matter as long as you get rid of the "slop" and secure it solidly. we used stainless sheetmetal to create wedges to help fix the slop.

if it were me, install brackets on the boat, set platform on the boat where you want it. mark holes, remove all and install. if you slide the platform brackets into the hull brackets, iirc they are able to swing from side to side a few inches so there's quite a bit of play in them.

sure you did this already but if those are the original brackets, check for cracks or issues. those pot metal brackets on the platform are crap and I would bet getting replacements today would be even more difficult than I had back in '09. there were a couple different sizes back in the day and most dealers were clueless to this.
watch the pins as well. the other issue with them and the slop is that it'll wear out the holes at the bottom of the platform brackets where the pins go through to secure and they eventually bust out.