No, don't do it that way.

Set ambient to 27.
Set T1 to 37.8
Set T2 to -168

Then you want load cases such as this:

1) W+T1+P1 (OPE)
2) W+T2+P1 (OPE)
3) W+P1 (SUS)
4) L1-L3 (EXP)
5) L2-L3 (EXP)
6) L1-L2 (EXP) {this will likely be the governing EXP case}