The B31.3 is not clear on whether or not the occasional stress should contribute to the maximum Sl stress used in the allowable computation for the expansion case. If you setup case 5, CAESAR II will use it in determining the maximum Sl. CAESAR II will use the max of L2, L3, and L5 as you state above.

For the wind evaluation (SUS + OCC)I would recommend:

Ln = L4 - L1 (OCC), this gives you the effect of wind considering non-linear boundary conditions. This is a construction case, not a code compliance case.

L3 + Ln (OCC), this is the code compliance case.

(What is your case 9 above, it looks like EXP+Alt_SUS?)