FLDVR:
The Crotch strap is just under "Soprano tight". [...] There is no way I can dive comfortably and in easy trim with the waist belt going across the middle of my abdomen plain and simple...
That sounds like it might be a little too tight. You want the waist strap to be around your waist, right about where your navel is. The crotch strap should be snug, but not so tight that you can't slip your hand under it (usually this means no more than an inch or so of slack). There is
a picture on the BAUE web site that illustrates everything pretty well. Please ignore the folded under crotch ring.
I think that if your harness were adjusted properly, then you would find that the perceived problems with comfort and trim would not be an issue.
FLDVR:
This is why the spg needs a longer hose to reach the belt pulled down to the bottom of my abdomen. Also with the waistbelt pulled lower it is easier to arch my back and lift my thighs up making trim a lot easier.
This may seem like a minor nit, but the SPG should hang at the
hip, not at the "bottom of the abdomen". If that is where yours is hanging, then your HP hose is definitely too long.
Again, I think the problems you are experiencing are due to a poorly adjusted harness. I am 6'1", and have my harness adjusted exactly as described above. I use a 24" SPG hose with my Scubapro first stage, which is just about perfect. I have no problems arching my back. As for the thighs, those should stay relatively flat, with minimal to no "lifting" during your kicks. Most of the kicing motion comes from the knees down, with the thighs moving mostly in the horizontal plain, if at all.
FLDVR:
The bottom line is that I'm suspicious of the one size fits all back plate.
As a previous poster pointed out, the height and torso length are less of an issue than most people think. With the backplate and harness positioned and adjusted properly, most people will find the distance from the first stage to the left hip to be fairly consistent (about 24", in fact ...
).
To be sure, there will be some folks who are "out-lyers", but they will be rare, and at the extremes for height. I have seen a standard backplate adjusted to properly fit a wide range of folks, from small (~5 feet) to large (well over 6 feet).
In any event, it's going to be a sub-optimal (and potentially frustrating) system to use until you get it properly dialed in. I think you should probably talk to the manufacturer of your plate (or perhaps the shop that sold it to you) to help you get this sorted out. Alternatively, you might consider taking a Fundamentals course to get some more hands-on assistance with the fine tuning.