I have some turned mounts for the shocks, that stick out about 18mm, the shocks won't be at an angle - they will be straight as they are supposed to. Also, the mounts are not on the center of the tube, they are about 3/4 the way to the outside on the top tube, and cross the center line for the down tubes (since they are at a weird angle)
I brought this up in my post while mocking it up, that I was considering using 4 plates on the outside of the frame how you describe, but decided against it as I saw 10 builds the way I have done it, and only 1 the way you described. TC bros, Dime City Cycles, Cognito Moto all have "kits" that do it this way, and i called Cognito, they assured me it was plenty strong for a bike shock mount. if it were indeed a gusset on a frame for strength or a car - things would be different
I very much appretiate your input and I am not dissagreing or discounting it. We've talked about "experts" before that steer people in the wrong direction and I know you're not one of them. i just feel confident in what i've done so far. If it turns out to be a problem (and it will be monitored) then I can always redo it... it's just metal