Originally Posted by pulsepb
. . . as far as my mounting to the frame Im confident it is sufficent as well. The 1/2 bolts are torque to a spec of 106 lb-ft and the 7/16' bolts to 69 lb-ft. this creates a sufficient pre-load where the friction of the plate on the frame is so great that the bolts will never see any shear effects as long as it it under the calculated load. . .
Don't assume that the preload is uniformly distributed over the surface area; it tends to concentrate under the head of the bolt which in turn can lead to very high surface shear stress in that region.
30K lbs is a ridiculously high design load for a winch pull; 10k is much more realistic although you can certainly generate more with a double line pull. As a point of reference, the factory tow hooks are rated for something like 5K lbs.
Doing a simple strength of materials calculation by making assumptions about the stress distribution (that its uniform) ignores stress concentrations arising from geometric discontinuities (holes). Bearing stress from the bolt shank on the hole combined with frictional shearing stress that also happens to concentrate in the same area can easily exceed the yield stress of the material at a load much smaller than 30K lbs. Another point to consider is that the load will not distribute evenly to all the bolts; the lions share will be felt by the front bolt(s).
I believe the OP's design is plenty adequate for normal recovery loads.