Hi Craig,
I'm just going to preface the following comments: While my Engineering studies weren't exactly successful degree/diploma wise, every class I took that had to do with building or fabrication and analysis I was REALLY good at. While at SIAST in Mechanical Engineering Technology my 2nd year design project was the finite element analysis of a bike I designed using an early version of Pro-E. I may be a bit rusty but I'm hoping you find this of value or at the very least interesting discussion:
Attachment:
Forces v1.jpg
Excuse the crude MS Paint - but I'm hoping this helps convey what I'm seeing. Shock forces (Sf) are essentially push pull along the mounting points of the coil over. The top mount forces will create a moment of force to the top of the assembly (Sf * distance to mount= Tf), and that force will then be creating a moment of force on the base of the upright (Tf *distance to base). What I see is that the welds opposing that force are ~2" apart which would be a lot of force acting on those welds. Add to this that the loads are going to be constantly cyclical, with the potential for some pretty high impact loads should the coil over have the bump stop integrated into it.
Attachment:
Cross bar forces v1.jpg
With just the cross bar I see it being essentially a box, and without any triangulation the forces incurred on one upright will transmit to the other upright in the same fashion stressing the base welding even more. While I'm sure the welds are likely fine for the loads it will see, they will still be very high, and with the constant and varying cyclical loads I'd worry about fatigue on the upright welds attaching to the subframe.
Attachment:
Bracing ideas v1.jpg
By trangulating the two uprights together the shock forces seen by the uprights would then get transmited and dispersed to other areas, and by spreading the loads to different areas of the sub frame any concerns would be considerably reduced.
Now I'm not there, and so much can be missed with just what I've seen in your posts. You could be absolutely right in saying it's been over built - and it should be fine, but I'm just offering ideas based on what I see and advice I would offer based on that.
Rabin