You really ought to consider a split keyboard. I'm also broad-shouldered, and the Advantage still caused inward rotation of my arms (i.e. activating my chest muscles to pull my hands inward).
With split keyboards, you can place the two halves as far apart as you want, tent them (rotate them outward), etc. It's really an RSI game changer, especially if you have a sit/stand desk.
I think Kinesis is coming out with a split board version of it soon, but the Moonlander and Ergodox EZ are also good options you can get now (I have these).