Hi, I have the same issue, sasapack is such a useful score, but the packstat app is not available to my knowledge in the latest r3.1 release. SMLewis suggestion to use fixbb from r2.3 with -natrot works well, but my preferred way to go for now is to use score mode with the following cmd line:
rosetta.macgcc -score -fa_input -scorefxn 12 -atom_vdw_set highres -find_disulf -decoystats -scorefile score12 -fa_output -nstruct 1 -no_optH -s
The -no_optH is important to score the identical structure without any atoms changing before/after the scoring. Even if you use fixbb for scoring, you should still use this flag.