How about some real world data? Hole 16 on Highbridge Gold is a wide open 270 feet with an 8 foot net drop to a roughly circular island green around 70 ft diameter. The pin is on a 2' elevated mound located 15' from the front edge. The moat surrounding the green is about 20' wide. Only the moat is OB so players can play up short of the moat and then attempt a long putt/short approach at the pin. If players go in the moat off the tee, they next play from the white tee 185' out as the drop zone.
For Blue level 950 rating, the scoring average was 2.86 with 36% 2s, 37% 3s, 21% 4s and 5% 5s. For Gold level, it's 2.60 average.
Rater of the tossed arc.