These are few of the challenges to run a PGS:
Age group: You need to decide how many age group categories who will have. You don't want to run 12yrs old against 21. Once qualifs completed, you need to establish ranking per category and then run finals for each. This quickly become a long afternoon, unless you decide to make "top 4" only finals.
Equipment: the starting gates is a major issue. You need 2 starting gates, 25-30 feet apart that open simultaneously for finals. Those are pretty rare at a typical ski hill. The backup is a SBX starting gates, wide enough with the first turn set 25+ feet apart the riders.
Ski hill: You need the widest possible run, with no "leaning" effect. Since both riders go together 30 feet apart, you need to install more safety net ( Bnet ) to cover potential fall or collision from any of the two riders. Leaning: if the run leans, this may create advantage for one of the riders. From that run, you need fast access to a lift: in the afternoon, each competitors will make many runs ( for a "top 16" format, the podium makes 8 runs during the afternoon ). At World Cup level, they use 4+ Ski-Doos to bring back competitors at the start.
Timing: You need a good timing operator, there is a lot of more things going on, vs a regular 2-run race. You need 2 different set-up, qualifs vs finals. There is no "2nd chance" to look back at data in the afternoon.
Alternative: In our provincial series, we make "2 best of 3+" format. Racers make 3 or 4 runs in a GS course, and we keep only the best 2 for ranking. Racers need to adjust themselves after each run to push further or establish a "base" time vs others. This create interesting situation & challenge since the race conditions change and get icy also.