I am considering a few options.
As I dive on a 15.7” long aluminum backplate now and it’s feels ok, the standard Halcyon steel plate may work. It’s 15.3” tall. This would forego having to use an STA as it has slots built in. I fear the additional 2.2 lbs for the STA may overweight me. (I use 4-6 lbs in pockets and the aluminum plate is 1.10 lbs).
Another option is an Oxycheq small steel plate that is 4 lbs and 13” long. The medium is 5 lbs and 15” long. I would probably need to add a bit of weight.
1. Standard Halcyon steel plate no STA (6 lbs) possibly no extra weight needed
2. Small Halcyon steel plate with STA (7 lbs) (maybe slightly overweighted)
3. Small Oxycheq steel plate (4 lbs) would need extra weight
4. Medium Oxycheq steel plate (5lbs) would need extra weight
Would a smaller bp be better? Feel different? I don’t know. I’ve never tried one. I almost always have a 3 or 5mm wetsuit on. If it’s very warm, a Lavacore suit.
I am still waiting to see how far from the top of the list I am for the Freedom plate. Those are 3 lbs but I think the comfort difference would be pretty big. Maybe??
ETA: I found some lighter weight STA’s. Paired with the small Halcyon, could work best.
My wife needed the smaller plate due to how the regular plate didnt work with her body morphology and was hitting her past her waist. I posted pictures of her in the thread I linked to earlier that shows her wearing the full size plate and photos of her wearing the small plate.
If you will be underweight with a small plate, you can ziptie a couple pinds of lead to the plate in strategic areas to keep you in good trimmed dive position, tou can thread a brick or to on tour cam straps, or there are different pocket solutions on the market.
I would be more concerned with how the plate fit compared to body size/shape and worry less about how much and where you will carry your lead...as any change in exposure suit and a few other factors such as fresh/sea water, or the salinity of the region you find yourself diving in may change how much lead you need.
-Z