At 52km, the 66" Ion S should be fine. Should you progress into 55-58km and start shortening the line you may want to size down to a 65".
I'm also on an Ion S and in between sizes and actually prefer the larger ski where I'm at the bottom of the recommended weight range.
Slow the boat down and ski for fun. Normally ski at 34.2, so ski a set at 30.4 and keep cutting the line till I miss.
Or challenge a ski partner to a "how slow can you go" competition. Start at your opener and keep slowing the boat down in tournament increments to see who can run the slowest pass.
Both actually force me to use good position and technique while also providing the most laughs/smiles.
@Anderson Like you I also went from a 2016 Vapor to a 2019 Vapor. Never felt as comfortable/stable on the '19 as I did the '16. Last season picked up the D3 Ion S and after some fin adjusting, the ski feels rock solid in the turns and fast cross course all with less effort on my part.
Set up CG fin on a 2019 Vapor. DFT +.020", FL -.020", FD +.010", 9 deg STD wing worked well on both stock S/D and L/S fin settings. Liked S/D better with the standard fin but prefer L/S with the CG fin.
On the 2016/2017 Vapor, I was always happiest with the stock settings. You'll still get the tip down attitude but the ski will cast out better in preturn (more carve, less point)
The T.R.A. should be just fine for you. The only difference between the T.R.A., Lyric, and Senate Alloy is flex. The T.R.A. has the softest flex pattern. Since you are at the bottom or the weight range for a 65" ski and are not skiing the course, the softer flex of the T.R.A. won't matter. Go ski and have fun!
@Midvkski I'm on 2016 with long/shallow setup and after alot of fin adjustments settled on stock everything with DFT +.015" (was at stock DFT +.020" but moved the fin back a little with recent water temp drop here in MI).
Not sure how the ski is feeling for you currently, but if you're looking for a starting point I'd try taking out a little length and DFT and wing back to 9 and see how it feels. Try 6.975, 2.450, .785, Radar wing 9, 30-5/8
@gregy keep your length and depth the same and try moving fin forward. I'm running long/shallow stock settings on a vapor and ended up adding .015" to DFT.