Depends on what you want.
Massey's is probably open enough that you could see people mostly punching the controls and you would keep more of a pack together.
A denser forest would result in less packing.
Crossing the road to Hellfire would be a bad idea for a mass start I think as if there is a car coming, people are more likely to risk it to get a gap (aka Tour de France level crossing).
Yeah but I think at night it would be ok. Especially with like a big flower loop. Could be a bit of craic. Any other suggestions?