[abl1111]

Thx guys. I installed the brackets and swim platform via drilling oversize holes and using epoxy. A few things I found that might be yseful for the next guy doing this:

First, I bought a drill guide @ Home Depot, by "General" for about $35 - this allowed me to drill the oversize holes exactly perpendicular to the transom - then, after I epoxied these holes, I was able to use this guide again to re-drill the smaller bolt holes at an exact perpendicular again, assuring that this bolt hole stays within the epoxy I've set.

Next, when injecting the epoxy, I used a large syringe ( no needle ) that I could not find anywhere! except, finally at a medical supply store for a cheap $1.25 a pc... Perfect to inject the thickened epoxy.
If you have two people to work on the epoxy, I would recommend a different approach - having one person in the boat, the other on the outside. Make epoxy to mayonnaise consistency. Tape off all areas around each hole first. Then, with a plastic spreader, 'jam' epoxy into the hole from the outside - in. As it come through the hole, the guy in the inside will 'catch' the epoxy with his spreader, wiping it on a pc of cardboard ( or something ), until the flow of epoxy coming out is an even flow - then you know that the epoxy has filled the drilled hole, with no air voids.

Repeat with each hole... The epoxy cured and I drilled through it and then installed brackets, via bolts, Boat Life, washers, locknuts... and finally the platform.. The thing is rock solid !