You can try performing FEA using the two cases:

1) Rpad ----> Pipe/Pad welded at the edge of pad.
2) Clamp----> Pipe/Clamp in Contact but not welded.

But I'm not sure if case 2 will run in FEA since the boundary condition is not well defined and may not generate the stiffness matrix for the whole assembly. I am thinking, due to high loads there might be some portion of clamp which will not be in contact with pipe due to ovalization. This will be a non-linear scenario.

The D/T for this case is 148 and with high concentrated loads at the corner junction of shoe/pipe may cause localized buckling or ovalization. You can check this using ASME VIII Div. 2 Design By Analysis for buckling and stresses.

In lieu of FEA, maybe there are proven standards already used for this size and working successfully. I'm not sure if physical testing will be costly for this case.

The pipeline folks may have a bunch of experience regarding this matter and may give you a more practical and not so complicated approach.

Just correct me if any wrong statement is made above.

Cheers!!!